81810669831 has 128 divisors (see below), whose sum is σ = 133092191232. Its totient is φ = 44126208000.

The previous prime is 81810669827. The next prime is 81810669859. The reversal of 81810669831 is 13896601818.

It is not a de Polignac number, because 81810669831 - 2² = 81810669827 is a prime.

It is a super-2 number, since 2×81810669831² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81810669431) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 179016555 + ... + 179017011.

It is an arithmetic number, because the mean of its divisors is an integer number (1039782744).

Almost surely, 2^81810669831 is an apocalyptic number.

81810669831 is a deficient number, since it is larger than the sum of its proper divisors (51281521401).

81810669831 is a wasteful number, since it uses less digits than its factorization.

81810669831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 753.

The product of its (nonzero) digits is 497664, while the sum is 51.

The spelling of 81810669831 in words is "eighty-one billion, eight hundred ten million, six hundred sixty-nine thousand, eight hundred thirty-one".