20817439 has 2 divisors, whose sum is σ = 20817440. Its totient is φ = 20817438.

The previous prime is 20817431. The next prime is 20817443. The reversal of 20817439 is 93471802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20817439 - 2³ = 20817431 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20817431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10408719 + 10408720.

It is an arithmetic number, because the mean of its divisors is an integer number (10408720).

Almost surely, 2^20817439 is an apocalyptic number.

20817439 is a deficient number, since it is larger than the sum of its proper divisors (1).

20817439 is an equidigital number, since it uses as much as digits as its factorization.

20817439 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 20817439 is about 4562.6131766785. The cubic root of 20817439 is about 275.0906103617.

The spelling of 20817439 in words is "twenty million, eight hundred seventeen thousand, four hundred thirty-nine".