81377831824 has 15 divisors (see below), whose sum is σ = 157671760017. Its totient is φ = 40688345376.

The previous prime is 81377831803. The next prime is 81377831893. The reversal of 81377831824 is 42813877318.

The square root of 81377831824 is 285268.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 20056224400 + 61321607424 = 141620^2 + 247632^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1105414 + ... + 1176730.

Almost surely, 2^81377831824 is an apocalyptic number.

81377831824 is the 285268-th square number.

It is an amenable number.

81377831824 is a deficient number, since it is larger than the sum of its proper divisors (76293928193).

81377831824 is an frugal number, since it uses more digits than its factorization.

81377831824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142642 (or 71319 counting only the distinct ones).

The product of its digits is 1806336, while the sum is 52.

The spelling of 81377831824 in words is "eighty-one billion, three hundred seventy-seven million, eight hundred thirty-one thousand, eight hundred twenty-four".