81517651572 has 24 divisors (see below), whose sum is σ = 217380404416. Its totient is φ = 23290757568.

The previous prime is 81517651571. The next prime is 81517651603. The reversal of 81517651572 is 27515671518.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81517651571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 485224033 + ... + 485224200.

Almost surely, 2^81517651572 is an apocalyptic number.

It is an amenable number.

81517651572 is an abundant number, since it is smaller than the sum of its proper divisors (135862752844).

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

81517651572 is a wasteful number, since it uses less digits than its factorization.

81517651572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 970448247 (or 970448245 counting only the distinct ones).

The product of its digits is 588000, while the sum is 48.

The spelling of 81517651572 in words is "eighty-one billion, five hundred seventeen million, six hundred fifty-one thousand, five hundred seventy-two".