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81385941 = 37132411237
BaseRepresentation
bin1001101100111…
…01100111010101
312200010211112010
410312131213111
5131313322231
612024214433
72005524540
oct466354725
9180124463
1081385941
1141a3850a
122330a419
1313b27180
14ab47857
157229546
hex4d9d9d5

81385941 has 32 divisors (see below), whose sum is σ = 134219008. Its totient is φ = 42716160.

The previous prime is 81385939. The next prime is 81385963. The reversal of 81385941 is 14958318.

It is not a de Polignac number, because 81385941 - 21 = 81385939 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81385941.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81385921) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65175 + ... + 66411.

It is an arithmetic number, because the mean of its divisors is an integer number (4194344).

It is the magic constant of a 546 × 546 magic square.

Almost surely, 281385941 is an apocalyptic number.

It is an amenable number.

81385941 is a deficient number, since it is larger than the sum of its proper divisors (52833067).

81385941 is a wasteful number, since it uses less digits than its factorization.

81385941 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1501.

The product of its digits is 34560, while the sum is 39.

The square root of 81385941 is about 9021.4156871303. The cubic root of 81385941 is about 433.3609717414.

It can be divided in two parts, 8138594 and 1, that added together give a triangular number (8138595 = T4034).

The spelling of 81385941 in words is "eighty-one million, three hundred eighty-five thousand, nine hundred forty-one".

Divisors: 1 3 7 13 21 39 91 241 273 723 1237 1687 3133 3711 5061 8659 9399 16081 21931 25977 48243 65793 112567 298117 337701 894351 2086819 3875521 6260457 11626563 27128647 81385941