20861539 has 2 divisors, whose sum is σ = 20861540. Its totient is φ = 20861538.

The previous prime is 20861521. The next prime is 20861549. The reversal of 20861539 is 93516802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20861539 - 2²¹ = 18764387 is a prime.

It is not a weakly prime, because it can be changed into another prime (20861509) 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 as a sum of consecutive naturals, namely, 10430769 + 10430770.

It is an arithmetic number, because the mean of its divisors is an integer number (10430770).

Almost surely, 2^20861539 is an apocalyptic number.

20861539 is a deficient number, since it is larger than the sum of its proper divisors (1).

20861539 is an equidigital number, since it uses as much as digits as its factorization.

20861539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 20861539 is about 4567.4433767700. The cubic root of 20861539 is about 275.2847254890.

The spelling of 20861539 in words is "twenty million, eight hundred sixty-one thousand, five hundred thirty-nine".