20861899 has 2 divisors, whose sum is σ = 20861900. Its totient is φ = 20861898.

The previous prime is 20861891. The next prime is 20861903. The reversal of 20861899 is 99816802.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20861899 - 2³ = 20861891 is a prime.

It is not a weakly prime, because it can be changed into another prime (20861891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10430949 + 10430950.

It is an arithmetic number, because the mean of its divisors is an integer number (10430950).

Almost surely, 2^20861899 is an apocalyptic number.

20861899 is a deficient number, since it is larger than the sum of its proper divisors (1).

20861899 is an equidigital number, since it uses as much as digits as its factorization.

20861899 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 20861899 is about 4567.4827859555. The cubic root of 20861899 is about 275.2863089761.

The spelling of 20861899 in words is "twenty million, eight hundred sixty-one thousand, eight hundred ninety-nine".