81362565720 has 80 divisors (see below), whose sum is σ = 273468634560. Its totient is φ = 21696683328.

The previous prime is 81362565649. The next prime is 81362565761. The reversal of 81362565720 is 2756526318.

81362565720 is a `hidden beast` number, since 8 + 1 + 3 + 62 + 565 + 7 + 20 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

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 polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12552712 + ... + 12559191.

It is an arithmetic number, because the mean of its divisors is an integer number (3418357932).

Almost surely, 2^81362565720 is an apocalyptic number.

It is an amenable number.

81362565720 is an abundant number, since it is smaller than the sum of its proper divisors (192106068840).

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

81362565720 is a wasteful number, since it uses less digits than its factorization.

81362565720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25111926 (or 25111913 counting only the distinct ones).

The product of its (nonzero) digits is 604800, while the sum is 45.

The spelling of 81362565720 in words is "eighty-one billion, three hundred sixty-two million, five hundred sixty-five thousand, seven hundred twenty".