20811899 has 2 divisors, whose sum is σ = 20811900. Its totient is φ = 20811898.

The previous prime is 20811883. The next prime is 20811907. The reversal of 20811899 is 99811802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20811899 - 2⁴ = 20811883 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20811799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10405949 + 10405950.

It is an arithmetic number, because the mean of its divisors is an integer number (10405950).

Almost surely, 2^20811899 is an apocalyptic number.

20811899 is a deficient number, since it is larger than the sum of its proper divisors (1).

20811899 is an equidigital number, since it uses as much as digits as its factorization.

20811899 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 20811899 is about 4562.0060280539. The cubic root of 20811899 is about 275.0662055475.

The spelling of 20811899 in words is "twenty million, eight hundred eleven thousand, eight hundred ninety-nine".