81684969631 has 8 divisors (see below), whose sum is σ = 81804821504. Its totient is φ = 81565169400.

The previous prime is 81684969623. The next prime is 81684969647. The reversal of 81684969631 is 13696948618.

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 81684969631 - 2³ = 81684969623 is a prime.

It is a super-2 number, since 2×81684969631² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81684969631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81684969661) 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 7 ways as a sum of consecutive naturals, for example, 4064650 + ... + 4084696.

It is an arithmetic number, because the mean of its divisors is an integer number (10225602688).

Almost surely, 2^81684969631 is an apocalyptic number.

81684969631 is a deficient number, since it is larger than the sum of its proper divisors (119851873).

81684969631 is a wasteful number, since it uses less digits than its factorization.

81684969631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25821.

The product of its digits is 13436928, while the sum is 61.

The spelling of 81684969631 in words is "eighty-one billion, six hundred eighty-four million, nine hundred sixty-nine thousand, six hundred thirty-one".