81615620436 has 24 divisors (see below), whose sum is σ = 217641654720. Its totient is φ = 23318748672.

The previous prime is 81615620417. The next prime is 81615620483. The reversal of 81615620436 is 63402651618.

It is a super-2 number, since 2×81615620436² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 485807181 + ... + 485807348.

It is an arithmetic number, because the mean of its divisors is an integer number (9068402280).

Almost surely, 2^81615620436 is an apocalyptic number.

It is an amenable number.

81615620436 is an abundant number, since it is smaller than the sum of its proper divisors (136026034284).

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

81615620436 is a wasteful number, since it uses less digits than its factorization.

81615620436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971614543 (or 971614541 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The spelling of 81615620436 in words is "eighty-one billion, six hundred fifteen million, six hundred twenty thousand, four hundred thirty-six".