561945591 has 72 divisors (see below), whose sum is σ = 922377456. Its totient is φ = 328373760.

The previous prime is 561945569. The next prime is 561945611. The reversal of 561945591 is 195549165.

It is a happy number.

561945591 is a `hidden beast` number, since 5 + 6 + 1 + 94 + 559 + 1 = 666.

It is not a de Polignac number, because 561945591 - 2¹³ = 561937399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561945511) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 4289596 + ... + 4289726.

It is an arithmetic number, because the mean of its divisors is an integer number (12810798).

Almost surely, 2^561945591 is an apocalyptic number.

561945591 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

561945591 is a deficient number, since it is larger than the sum of its proper divisors (360431865).

561945591 is a wasteful number, since it uses less digits than its factorization.

561945591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253 (or 227 counting only the distinct ones).

The product of its digits is 243000, while the sum is 45.

The square root of 561945591 is about 23705.3916019120. The cubic root of 561945591 is about 825.2105203803.

The spelling of 561945591 in words is "five hundred sixty-one million, nine hundred forty-five thousand, five hundred ninety-one".