81757931 has 8 divisors (see below), whose sum is σ = 89029200. Its totient is φ = 74783520.

The previous prime is 81757927. The next prime is 81757997. The reversal of 81757931 is 13975718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81757931 - 2² = 81757927 is a prime.

It is a super-2 number, since 2×81757931² = 13368718562801522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81757631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73640 + ... + 74741.

It is an arithmetic number, because the mean of its divisors is an integer number (11128650).

Almost surely, 2^81757931 is an apocalyptic number.

81757931 is a deficient number, since it is larger than the sum of its proper divisors (7271269).

81757931 is a wasteful number, since it uses less digits than its factorization.

81757931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148429.

The product of its digits is 52920, while the sum is 41.

The square root of 81757931 is about 9042.0092346779. The cubic root of 81757931 is about 434.0202214027.

The spelling of 81757931 in words is "eighty-one million, seven hundred fifty-seven thousand, nine hundred thirty-one".