864519561 has 20 divisors (see below), whose sum is σ = 1347595392. Its totient is φ = 551286648.

The previous prime is 864519521. The next prime is 864519571. The reversal of 864519561 is 165915468.

864519561 is a `hidden beast` number, since 86 + 4 + 5 + 1 + 9 + 561 = 666.

It is not a de Polignac number, because 864519561 - 2⁶ = 864519497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (864519521) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 230161 + ... + 233886.

Almost surely, 2^864519561 is an apocalyptic number.

864519561 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

864519561 is a deficient number, since it is larger than the sum of its proper divisors (483075831).

864519561 is a wasteful number, since it uses less digits than its factorization.

864519561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 464082 (or 464073 counting only the distinct ones).

The product of its digits is 259200, while the sum is 45.

The square root of 864519561 is about 29402.7134972267. The cubic root of 864519561 is about 952.6315076655.

The spelling of 864519561 in words is "eight hundred sixty-four million, five hundred nineteen thousand, five hundred sixty-one".