815442561 has 12 divisors (see below), whose sum is σ = 1218477780. Its totient is φ = 524882400.

The previous prime is 815442557. The next prime is 815442601. The reversal of 815442561 is 165244518.

It is a happy number.

815442561 is a `hidden beast` number, since 8 + 1 + 54 + 42 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 265070961 + 550371600 = 16281^2 + 23460^2 .

It is not a de Polignac number, because 815442561 - 2² = 815442557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (815442541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1561890 + ... + 1562411.

It is an arithmetic number, because the mean of its divisors is an integer number (101539815).

Almost surely, 2^815442561 is an apocalyptic number.

It is an amenable number.

815442561 is a deficient number, since it is larger than the sum of its proper divisors (403035219).

815442561 is a wasteful number, since it uses less digits than its factorization.

815442561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3124336 (or 3124333 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The square root of 815442561 is about 28555.9549131175. The cubic root of 815442561 is about 934.2529081250.

It can be divided in two parts, 815442 and 561, that added together give a triangular number (816003 = T₁₂₇₇).

The spelling of 815442561 in words is "eight hundred fifteen million, four hundred forty-two thousand, five hundred sixty-one".