81940569531 has 16 divisors (see below), whose sum is σ = 112246815744. Its totient is φ = 53144605184.

The previous prime is 81940569527. The next prime is 81940569569. The reversal of 81940569531 is 13596504918.

It is a cyclic number.

It is not a de Polignac number, because 81940569531 - 2² = 81940569527 is a prime.

It is a super-2 number, since 2×81940569531² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81940569631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1716390 + ... + 1763483.

It is an arithmetic number, because the mean of its divisors is an integer number (7015425984).

Almost surely, 2^81940569531 is an apocalyptic number.

81940569531 is a deficient number, since it is larger than the sum of its proper divisors (30306246213).

81940569531 is a wasteful number, since it uses less digits than its factorization.

81940569531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3480090.

The product of its (nonzero) digits is 1166400, while the sum is 51.

The spelling of 81940569531 in words is "eighty-one billion, nine hundred forty million, five hundred sixty-nine thousand, five hundred thirty-one".