20399564 has 12 divisors (see below), whose sum is σ = 35887488. Its totient is φ = 10146000.

The previous prime is 20399537. The next prime is 20399567. The reversal of 20399564 is 46599302.

It is a super-2 number, since 2×20399564² = 832284422780192, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20399567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12587 + ... + 14114.

It is an arithmetic number, because the mean of its divisors is an integer number (2990624).

Almost surely, 2^20399564 is an apocalyptic number.

It is an amenable number.

20399564 is a deficient number, since it is larger than the sum of its proper divisors (15487924).

20399564 is a wasteful number, since it uses less digits than its factorization.

20399564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26896 (or 26894 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 38.

The square root of 20399564 is about 4516.5876499853. The cubic root of 20399564 is about 273.2374949878.

The spelling of 20399564 in words is "twenty million, three hundred ninety-nine thousand, five hundred sixty-four".