20564491 has 2 divisors, whose sum is σ = 20564492. Its totient is φ = 20564490.

The previous prime is 20564473. The next prime is 20564513. The reversal of 20564491 is 19446502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20564491 - 2⁵ = 20564459 is a prime.

It is not a weakly prime, because it can be changed into another prime (20564431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282245 + 10282246.

It is an arithmetic number, because the mean of its divisors is an integer number (10282246).

Almost surely, 2^20564491 is an apocalyptic number.

20564491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20564491 is an equidigital number, since it uses as much as digits as its factorization.

20564491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 20564491 is about 4534.8088162568. The cubic root of 20564491 is about 273.9718789404.

The spelling of 20564491 in words is "twenty million, five hundred sixty-four thousand, four hundred ninety-one".