81213724956672 has 2304 divisors, whose sum is σ = 317122922188800. Its totient is φ = 20147190497280.

The previous prime is 81213724956647. The next prime is 81213724956691. The reversal of 81213724956672 is 27665942731218.

It is a happy number.

81213724956672 is a `hidden beast` number, since 8 + 1 + 2 + 1 + 3 + 72 + 495 + 6 + 6 + 72 = 666.

It is a tau number, because it is divible by the number of its divisors (2304).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 118907356843 + ... + 118907357525.

It is an arithmetic number, because the mean of its divisors is an integer number (137640157200).

Almost surely, 2^{81213724956672} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81213724956672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158561461094400).

81213724956672 is an abundant number, since it is smaller than the sum of its proper divisors (235909197232128).

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

81213724956672 is a wasteful number, since it uses less digits than its factorization.

81213724956672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874 (or 842 counting only the distinct ones).

The product of its digits is 60963840, while the sum is 63.

The spelling of 81213724956672 in words is "eighty-one trillion, two hundred thirteen billion, seven hundred twenty-four million, nine hundred fifty-six thousand, six hundred seventy-two".