20787839 has 2 divisors, whose sum is σ = 20787840. Its totient is φ = 20787838.

The previous prime is 20787829. The next prime is 20787857. The reversal of 20787839 is 93878702.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20787839 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20787839.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20787829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393919 + 10393920.

It is an arithmetic number, because the mean of its divisors is an integer number (10393920).

Almost surely, 2^20787839 is an apocalyptic number.

20787839 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787839 is an equidigital number, since it uses as much as digits as its factorization.

20787839 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 169344, while the sum is 44.

The square root of 20787839 is about 4559.3682676441. The cubic root of 20787839 is about 274.9601661312.

The spelling of 20787839 in words is "twenty million, seven hundred eighty-seven thousand, eight hundred thirty-nine".