20561916 has 12 divisors (see below), whose sum is σ = 47977832. Its totient is φ = 6853968.

The previous prime is 20561911. The next prime is 20561917. The reversal of 20561916 is 61916502.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561911) 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, 856735 + ... + 856758.

Almost surely, 2^20561916 is an apocalyptic number.

It is an amenable number.

20561916 is an abundant number, since it is smaller than the sum of its proper divisors (27415916).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20561916 is a wasteful number, since it uses less digits than its factorization.

20561916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1713500 (or 1713498 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 20561916 is about 4534.5248924226. The cubic root of 20561916 is about 273.9604432568.

The spelling of 20561916 in words is "twenty million, five hundred sixty-one thousand, nine hundred sixteen".