81309765057 has 12 divisors (see below), whose sum is σ = 112023030960. Its totient is φ = 52457911080.

The previous prime is 81309765013. The next prime is 81309765091. The reversal of 81309765057 is 75056790318.

It is not a de Polignac number, because 81309765057 - 2¹⁹ = 81309240769 is a prime.

It is a super-2 number, since 2×81309765057² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81309715057) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14098707 + ... + 14104472.

It is an arithmetic number, because the mean of its divisors is an integer number (9335252580).

Almost surely, 2^81309765057 is an apocalyptic number.

It is an amenable number.

81309765057 is a deficient number, since it is larger than the sum of its proper divisors (30713265903).

81309765057 is a wasteful number, since it uses less digits than its factorization.

81309765057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28203244 (or 28203213 counting only the distinct ones).

The product of its (nonzero) digits is 1587600, while the sum is 51.

The spelling of 81309765057 in words is "eighty-one billion, three hundred nine million, seven hundred sixty-five thousand, fifty-seven".