20812139 has 2 divisors, whose sum is σ = 20812140. Its totient is φ = 20812138.

The previous prime is 20812123. The next prime is 20812147. The reversal of 20812139 is 93121802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20812139 - 2⁴ = 20812123 is a prime.

It is a Chen prime.

It is equal to p_1318832 and since 20812139 and 1318832 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (20812189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10406069 + 10406070.

It is an arithmetic number, because the mean of its divisors is an integer number (10406070).

Almost surely, 2^20812139 is an apocalyptic number.

20812139 is a deficient number, since it is larger than the sum of its proper divisors (1).

20812139 is an equidigital number, since it uses as much as digits as its factorization.

20812139 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 20812139 is about 4562.0323321958. The cubic root of 20812139 is about 275.0672628855.

The spelling of 20812139 in words is "twenty million, eight hundred twelve thousand, one hundred thirty-nine".