81905368 has 32 divisors (see below), whose sum is σ = 157790160. Its totient is φ = 39836160.

The previous prime is 81905359. The next prime is 81905377. The reversal of 81905368 is 86350918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81905359) and next prime (81905377).

It is a self number, because there is not a number n which added to its sum of digits gives 81905368.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156948 + ... + 157468.

Almost surely, 2^81905368 is an apocalyptic number.

It is an amenable number.

81905368 is a deficient number, since it is larger than the sum of its proper divisors (75884792).

81905368 is a wasteful number, since it uses less digits than its factorization.

81905368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1027 (or 1023 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 81905368 is about 9050.1584516516. The cubic root of 81905368 is about 434.2809594602.

The spelling of 81905368 in words is "eighty-one million, nine hundred five thousand, three hundred sixty-eight".