81492720867 has 24 divisors (see below), whose sum is σ = 125036648880. Its totient is φ = 52455070080.

The previous prime is 81492720847. The next prime is 81492720877. The reversal of 81492720867 is 76802729418.

It is a happy number.

81492720867 is a `hidden beast` number, since 8 + 1 + 492 + 72 + 0 + 86 + 7 = 666.

It is not a de Polignac number, because 81492720867 - 2⁸ = 81492720611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81492720847) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1771734 + ... + 1817147.

It is an arithmetic number, because the mean of its divisors is an integer number (5209860370).

Almost surely, 2^81492720867 is an apocalyptic number.

81492720867 is a gapful number since it is divisible by the number (87) formed by its first and last digit.

81492720867 is a deficient number, since it is larger than the sum of its proper divisors (43543928013).

81492720867 is a wasteful number, since it uses less digits than its factorization.

81492720867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3588948 (or 3588913 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 54.

The spelling of 81492720867 in words is "eighty-one billion, four hundred ninety-two million, seven hundred twenty thousand, eight hundred sixty-seven".