81717505072 has 20 divisors (see below), whose sum is σ = 180945904336. Its totient is φ = 35021787840.

The previous prime is 81717505063. The next prime is 81717505073. The reversal of 81717505072 is 27050571718.

It is not an unprimeable number, because it can be changed into a prime (81717505073) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364810179 + ... + 364810402.

Almost surely, 2^81717505072 is an apocalyptic number.

It is an amenable number.

81717505072 is an abundant number, since it is smaller than the sum of its proper divisors (99228399264).

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

81717505072 is a wasteful number, since it uses less digits than its factorization.

81717505072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729620596 (or 729620590 counting only the distinct ones).

The product of its (nonzero) digits is 137200, while the sum is 43.

The spelling of 81717505072 in words is "eighty-one billion, seven hundred seventeen million, five hundred five thousand, seventy-two".