81698540872 has 32 divisors (see below), whose sum is σ = 165242823480. Its totient is φ = 37644249600.

The previous prime is 81698540867. The next prime is 81698540921. The reversal of 81698540872 is 27804589618.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 74860243236 + 6838297636 = 273606^2 + 82694^2 .

It is a super-2 number, since 2×81698540872² (a number of 23 digits) contains 22 as substring.

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, 591043 + ... + 716050.

Almost surely, 2^81698540872 is an apocalyptic number.

It is an amenable number.

81698540872 is an abundant number, since it is smaller than the sum of its proper divisors (83544282608).

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

81698540872 is a wasteful number, since it uses less digits than its factorization.

81698540872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1307713 (or 1307709 counting only the distinct ones).

The product of its (nonzero) digits is 7741440, while the sum is 58.

The spelling of 81698540872 in words is "eighty-one billion, six hundred ninety-eight million, five hundred forty thousand, eight hundred seventy-two".