81491445268992 has 180 divisors, whose sum is σ = 258514441575390. Its totient is φ = 24694377185280.

The previous prime is 81491445268957. The next prime is 81491445269089. The reversal of 81491445268992 is 29986254419418.

It is a happy number.

81491445268992 is a `hidden beast` number, since 8 + 1 + 4 + 9 + 1 + 4 + 4 + 526 + 8 + 9 + 92 = 666.

It can be written as a sum of positive squares in only one way, i.e., 81071727872256 + 419717396736 = 9003984^2 + 647856^2 .

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a self number, because there is not a number n which added to its sum of digits gives 81491445268992.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 72520017 + ... + 73635152.

Almost surely, 2^{81491445268992} is an apocalyptic number.

It is an amenable number.

81491445268992 is an abundant number, since it is smaller than the sum of its proper divisors (177022996306398).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81491445268992 is a wasteful number, since it uses less digits than its factorization.

81491445268992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146155215 (or 146155185 counting only the distinct ones).

The product of its digits is 358318080, while the sum is 72.

The spelling of 81491445268992 in words is "eighty-one trillion, four hundred ninety-one billion, four hundred forty-five million, two hundred sixty-eight thousand, nine hundred ninety-two".