81692568921 has 16 divisors (see below), whose sum is σ = 111649285440. Its totient is φ = 53100430080.

The previous prime is 81692568889. The next prime is 81692568931. The reversal of 81692568921 is 12986529618.

It is a happy number.

It is not a de Polignac number, because 81692568921 - 2⁵ = 81692568889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81692568931) 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, 5980 + ... + 404253.

It is an arithmetic number, because the mean of its divisors is an integer number (6978080340).

Almost surely, 2^81692568921 is an apocalyptic number.

It is an amenable number.

81692568921 is a deficient number, since it is larger than the sum of its proper divisors (29956716519).

81692568921 is a wasteful number, since it uses less digits than its factorization.

81692568921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411896.

The product of its digits is 3732480, while the sum is 57.

The spelling of 81692568921 in words is "eighty-one billion, six hundred ninety-two million, five hundred sixty-eight thousand, nine hundred twenty-one".