81164393280 has 112 divisors (see below), whose sum is σ = 286329973440. Its totient is φ = 21643835904.

The previous prime is 81164393263. The next prime is 81164393293. The reversal of 81164393280 is 8239346118.

81164393280 is a `hidden beast` number, since 81 + 164 + 393 + 28 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4688374 + ... + 4705653.

It is an arithmetic number, because the mean of its divisors is an integer number (2556517620).

Almost surely, 2^81164393280 is an apocalyptic number.

81164393280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81164393280 is an abundant number, since it is smaller than the sum of its proper divisors (205165580160).

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

81164393280 is a wasteful number, since it uses less digits than its factorization.

81164393280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9394053 (or 9394037 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 45.

The spelling of 81164393280 in words is "eighty-one billion, one hundred sixty-four million, three hundred ninety-three thousand, two hundred eighty".