81961375392 has 480 divisors, whose sum is σ = 276623424000. Its totient is φ = 23583301632.

The previous prime is 81961375369. The next prime is 81961375411. The reversal of 81961375392 is 29357316918.

81961375392 is a `hidden beast` number, since 8 + 1 + 96 + 13 + 7 + 539 + 2 = 666.

It is a super-2 number, since 2×81961375392² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 113993209 + ... + 113993927.

It is an arithmetic number, because the mean of its divisors is an integer number (576298800).

Almost surely, 2^81961375392 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 81961375392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138311712000).

81961375392 is an abundant number, since it is smaller than the sum of its proper divisors (194662048608).

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

81961375392 is a wasteful number, since it uses less digits than its factorization.

81961375392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 970 (or 953 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 54.

The spelling of 81961375392 in words is "eighty-one billion, nine hundred sixty-one million, three hundred seventy-five thousand, three hundred ninety-two".