81292757 has 16 divisors (see below), whose sum is σ = 103283712. Its totient is φ = 62242560.

The previous prime is 81292753. The next prime is 81292769. The reversal of 81292757 is 75729218.

It is a cyclic number.

It is not a de Polignac number, because 81292757 - 2² = 81292753 is a prime.

It is a super-2 number, since 2×81292757² = 13217024681322098, which contains 22 as substring.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81292753) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11588 + ... + 17229.

It is an arithmetic number, because the mean of its divisors is an integer number (6455232).

Almost surely, 2^81292757 is an apocalyptic number.

It is an amenable number.

81292757 is a deficient number, since it is larger than the sum of its proper divisors (21990955).

81292757 is a wasteful number, since it uses less digits than its factorization.

81292757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28868.

The product of its digits is 70560, while the sum is 41.

The square root of 81292757 is about 9016.2496083460. The cubic root of 81292757 is about 433.1955142918.

The spelling of 81292757 in words is "eighty-one million, two hundred ninety-two thousand, seven hundred fifty-seven".