81951657984 has 585 divisors, whose sum is σ = 288850380951. Its totient is φ = 23084974080.

The previous prime is 81951657929. The next prime is 81951658043. The reversal of 81951657984 is 48975615918.

The square root of 81951657984 is 286272.

It is a perfect power (a square), and thus also a powerful number.

81951657984 is a `hidden beast` number, since 8 + 1 + 9 + 51 + 6 + 579 + 8 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

Its product of digits (21772800) is a multiple of the sum of its prime factors (192).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 1154248669 + ... + 1154248739.

Almost surely, 2^81951657984 is an apocalyptic number.

81951657984 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

81951657984 is the 286272-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81951657984

81951657984 is an abundant number, since it is smaller than the sum of its proper divisors (206898722967).

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

81951657984 is an frugal number, since it uses more digits than its factorization.

81951657984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192 (or 83 counting only the distinct ones).

The product of its digits is 21772800, while the sum is 63.

The spelling of 81951657984 in words is "eighty-one billion, nine hundred fifty-one million, six hundred fifty-seven thousand, nine hundred eighty-four".