815712861 has 4 divisors (see below), whose sum is σ = 1087617152. Its totient is φ = 543808572.

The previous prime is 815712847. The next prime is 815712893. The reversal of 815712861 is 168217518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 815712861 - 2⁵ = 815712829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815712061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135952141 + ... + 135952146.

It is an arithmetic number, because the mean of its divisors is an integer number (271904288).

Almost surely, 2^815712861 is an apocalyptic number.

It is an amenable number.

815712861 is a deficient number, since it is larger than the sum of its proper divisors (271904291).

815712861 is a wasteful number, since it uses less digits than its factorization.

815712861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271904290.

The product of its digits is 26880, while the sum is 39.

The square root of 815712861 is about 28560.6873341662. The cubic root of 815712861 is about 934.3561243317.

The spelling of 815712861 in words is "eight hundred fifteen million, seven hundred twelve thousand, eight hundred sixty-one".