81577070689 has 27 divisors (see below), whose sum is σ = 88603405387. Its totient is φ = 75092136704.

The previous prime is 81577070681. The next prime is 81577070753. The reversal of 81577070689 is 98607077518.

The square root of 81577070689 is 285617.

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

It can be written as a sum of positive squares in 13 ways, for example, as 42607152225 + 38969918464 = 206415^2 + 197408^2 .

It is not a de Polignac number, because 81577070689 - 2³ = 81577070681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81577070681) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 257340759 + ... + 257341075.

Almost surely, 2^81577070689 is an apocalyptic number.

81577070689 is the 285617-th square number.

81577070689 is the 142809-th centered octagonal number.

It is an amenable number.

81577070689 is a deficient number, since it is larger than the sum of its proper divisors (7026334698).

81577070689 is an frugal number, since it uses more digits than its factorization.

81577070689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 774 (or 387 counting only the distinct ones).

The product of its (nonzero) digits is 5927040, while the sum is 58.

The spelling of 81577070689 in words is "eighty-one billion, five hundred seventy-seven million, seventy thousand, six hundred eighty-nine".