20670561 has 6 divisors (see below), whose sum is σ = 29857490. Its totient is φ = 13780368.

The previous prime is 20670557. The next prime is 20670563. The reversal of 20670561 is 16507602.

It can be written as a sum of positive squares in only one way, i.e., 19580625 + 1089936 = 4425^2 + 1044^2 .

It is not a de Polignac number, because 20670561 - 2² = 20670557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20670563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1148356 + ... + 1148373.

Almost surely, 2^20670561 is an apocalyptic number.

It is an amenable number.

20670561 is a deficient number, since it is larger than the sum of its proper divisors (9186929).

20670561 is a wasteful number, since it uses less digits than its factorization.

20670561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2296735 (or 2296732 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 20670561 is about 4546.4888650474. The cubic root of 20670561 is about 274.4421130685.

The spelling of 20670561 in words is "twenty million, six hundred seventy thousand, five hundred sixty-one".