1645712640 has 864 divisors, whose sum is σ = 7124697216. Its totient is φ = 358318080.

The previous prime is 1645712639. The next prime is 1645712647. The reversal of 1645712640 is 462175461.

1645712640 is a `hidden beast` number, since 1 + 6 + 4 + 5 + 7 + 1 + 2 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1645712595 and 1645712604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645712647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 44478702 + ... + 44478738.

Almost surely, 2^1645712640 is an apocalyptic number.

1645712640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1645712640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3562348608).

1645712640 is an abundant number, since it is smaller than the sum of its proper divisors (5478984576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1645712640 is a wasteful number, since it uses less digits than its factorization.

1645712640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 1645712640 is about 40567.3839432616. The cubic root of 1645712640 is about 1180.6413826200.

The spelling of 1645712640 in words is "one billion, six hundred forty-five million, seven hundred twelve thousand, six hundred forty".