81377247690 has 48 divisors (see below), whose sum is σ = 211952824200. Its totient is φ = 21662447616.

The previous prime is 81377247689. The next prime is 81377247713. The reversal of 81377247690 is 9674277318.

81377247690 is a `hidden beast` number, since 8 + 13 + 7 + 72 + 476 + 90 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 26788196241 + 54589051449 = 163671^2 + 233643^2 .

It is a super-2 number, since 2×81377247690² (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 23 ways as a sum of consecutive naturals, for example, 743335 + ... + 845754.

Almost surely, 2^81377247690 is an apocalyptic number.

81377247690 is an abundant number, since it is smaller than the sum of its proper divisors (130575576510).

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

81377247690 is a wasteful number, since it uses less digits than its factorization.

81377247690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1589671 (or 1589668 counting only the distinct ones).

The product of its (nonzero) digits is 3556224, while the sum is 54.

The spelling of 81377247690 in words is "eighty-one billion, three hundred seventy-seven million, two hundred forty-seven thousand, six hundred ninety".