647977439 has 2 divisors, whose sum is σ = 647977440. Its totient is φ = 647977438.

The previous prime is 647977433. The next prime is 647977507. The reversal of 647977439 is 934779746.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 647977439 - 2²⁴ = 631200223 is a prime.

It is a super-2 number, since 2×647977439² = 839749522905997442, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (647977433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323988719 + 323988720.

It is an arithmetic number, because the mean of its divisors is an integer number (323988720).

Almost surely, 2^647977439 is an apocalyptic number.

647977439 is a deficient number, since it is larger than the sum of its proper divisors (1).

647977439 is an equidigital number, since it uses as much as digits as its factorization.

647977439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8001504, while the sum is 56.

The square root of 647977439 is about 25455.4009789671. The cubic root of 647977439 is about 865.3396992924.

The spelling of 647977439 in words is "six hundred forty-seven million, nine hundred seventy-seven thousand, four hundred thirty-nine".