815913561 has 16 divisors (see below), whose sum is σ = 1169510400. Its totient is φ = 504348048.

The previous prime is 815913559. The next prime is 815913617. The reversal of 815913561 is 165319518.

It is not a de Polignac number, because 815913561 - 2¹ = 815913559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (815913541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 149601 + ... + 154958.

It is an arithmetic number, because the mean of its divisors is an integer number (73094400).

Almost surely, 2^815913561 is an apocalyptic number.

It is an amenable number.

815913561 is a deficient number, since it is larger than the sum of its proper divisors (353596839).

815913561 is a wasteful number, since it uses less digits than its factorization.

815913561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304628.

The product of its digits is 32400, while the sum is 39.

The square root of 815913561 is about 28564.2006889743. The cubic root of 815913561 is about 934.4327484746.

The spelling of 815913561 in words is "eight hundred fifteen million, nine hundred thirteen thousand, five hundred sixty-one".