815565520 has 160 divisors (see below), whose sum is σ = 2419845120. Its totient is φ = 248209920.

The previous prime is 815565511. The next prime is 815565523. The reversal of 815565520 is 25565518.

It is a self number, because there is not a number n which added to its sum of digits gives 815565520.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815565523) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 263341 + ... + 266419.

It is an arithmetic number, because the mean of its divisors is an integer number (15124032).

Almost surely, 2^815565520 is an apocalyptic number.

815565520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 815565520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1209922560).

815565520 is an abundant number, since it is smaller than the sum of its proper divisors (1604279600).

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

815565520 is a wasteful number, since it uses less digits than its factorization.

815565520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3153 (or 3147 counting only the distinct ones).

The product of its (nonzero) digits is 60000, while the sum is 37.

The square root of 815565520 is about 28558.1077804535. The cubic root of 815565520 is about 934.2998638254.

The spelling of 815565520 in words is "eight hundred fifteen million, five hundred sixty-five thousand, five hundred twenty".