864825561 has 12 divisors (see below), whose sum is σ = 1265006080. Its totient is φ = 569251800.

The previous prime is 864825557. The next prime is 864825571. The reversal of 864825561 is 165528468.

864825561 is a `hidden beast` number, since 8 + 6 + 4 + 82 + 5 + 561 = 666.

It is not a de Polignac number, because 864825561 - 2² = 864825557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (864825541) 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, 607465 + ... + 608886.

Almost surely, 2^864825561 is an apocalyptic number.

It is an amenable number.

864825561 is a deficient number, since it is larger than the sum of its proper divisors (400180519).

864825561 is a wasteful number, since it uses less digits than its factorization.

864825561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1216436 (or 1216433 counting only the distinct ones).

The product of its digits is 460800, while the sum is 45.

The square root of 864825561 is about 29407.9166382116. The cubic root of 864825561 is about 952.7438902605.

The spelling of 864825561 in words is "eight hundred sixty-four million, eight hundred twenty-five thousand, five hundred sixty-one".