20513539 has 4 divisors (see below), whose sum is σ = 21405456. Its totient is φ = 19621624.

The previous prime is 20513531. The next prime is 20513551. The reversal of 20513539 is 93531502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93531502 = 2 ⋅46765751.

It is a cyclic number.

It is not a de Polignac number, because 20513539 - 2³ = 20513531 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20513531) 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, 445924 + ... + 445969.

It is an arithmetic number, because the mean of its divisors is an integer number (5351364).

Almost surely, 2^20513539 is an apocalyptic number.

20513539 is a deficient number, since it is larger than the sum of its proper divisors (891917).

20513539 is an equidigital number, since it uses as much as digits as its factorization.

20513539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 891916.

The product of its (nonzero) digits is 4050, while the sum is 28.

The square root of 20513539 is about 4529.1874547208. The cubic root of 20513539 is about 273.7454212727.

The spelling of 20513539 in words is "twenty million, five hundred thirteen thousand, five hundred thirty-nine".