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1581681645 = 32543181551
BaseRepresentation
bin101111001000110…
…1000101111101101
311002020012202022200
41132101220233231
511214402303040
6420540532113
754124033515
oct13621505755
94066182280
101581681645
117418aa915
12381851039
131c28c0bcb
141100c6845
1593cd1630
hex5e468bed

1581681645 has 24 divisors (see below), whose sum is σ = 2747976192. Its totient is φ = 841596000.

The previous prime is 1581681631. The next prime is 1581681653. The reversal of 1581681645 is 5461861851.

1581681645 is a `hidden beast` number, since 1 + 581 + 6 + 8 + 1 + 64 + 5 = 666.

1581681645 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1581681645 - 25 = 1581681613 is a prime.

It is a super-3 number, since 3×15816816453 (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1581681645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21381 + ... + 60170.

It is an arithmetic number, because the mean of its divisors is an integer number (114499008).

Almost surely, 21581681645 is an apocalyptic number.

1581681645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1581681645 is a deficient number, since it is larger than the sum of its proper divisors (1166294547).

1581681645 is a wasteful number, since it uses less digits than its factorization.

1581681645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81993 (or 81990 counting only the distinct ones).

The product of its digits is 230400, while the sum is 45.

The square root of 1581681645 is about 39770.3613888534. The cubic root of 1581681645 is about 1165.1263519807.

It can be divided in two parts, 15816 and 81645, that added together give a triangular number (97461 = T441).

The spelling of 1581681645 in words is "one billion, five hundred eighty-one million, six hundred eighty-one thousand, six hundred forty-five".

Divisors: 1 3 5 9 15 45 431 1293 2155 3879 6465 19395 81551 244653 407755 733959 1223265 3669795 35148481 105445443 175742405 316336329 527227215 1581681645