561985621 has 4 divisors (see below), whose sum is σ = 562377600. Its totient is φ = 561593644.

The previous prime is 561985607. The next prime is 561985631. The reversal of 561985621 is 126589165.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 561985621 - 2⁷ = 561985493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561985601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 193831 + ... + 196708.

It is an arithmetic number, because the mean of its divisors is an integer number (140594400).

Almost surely, 2^561985621 is an apocalyptic number.

It is an amenable number.

561985621 is a deficient number, since it is larger than the sum of its proper divisors (391979).

561985621 is a wasteful number, since it uses less digits than its factorization.

561985621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391978.

The product of its digits is 129600, while the sum is 43.

The square root of 561985621 is about 23706.2359095661. The cubic root of 561985621 is about 825.2301144438.

The spelling of 561985621 in words is "five hundred sixty-one million, nine hundred eighty-five thousand, six hundred twenty-one".