20810639 has 2 divisors, whose sum is σ = 20810640. Its totient is φ = 20810638.

The previous prime is 20810633. The next prime is 20810651. The reversal of 20810639 is 93601802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20810639 - 2²⁰ = 19762063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20810633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10405319 + 10405320.

It is an arithmetic number, because the mean of its divisors is an integer number (10405320).

Almost surely, 2^20810639 is an apocalyptic number.

20810639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20810639 is an equidigital number, since it uses as much as digits as its factorization.

20810639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20810639 is about 4561.8679288204. The cubic root of 20810639 is about 275.0606543896.

The spelling of 20810639 in words is "twenty million, eight hundred ten thousand, six hundred thirty-nine".