646520839 has 2 divisors, whose sum is σ = 646520840. Its totient is φ = 646520838.

The previous prime is 646520807. The next prime is 646520843. The reversal of 646520839 is 938025646.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646520839 - 2⁵ = 646520807 is a prime.

It is a super-2 number, since 2×646520839² = 835978390522527842, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 646520795 and 646520804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646520899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323260419 + 323260420.

It is an arithmetic number, because the mean of its divisors is an integer number (323260420).

Almost surely, 2^646520839 is an apocalyptic number.

646520839 is a deficient number, since it is larger than the sum of its proper divisors (1).

646520839 is an equidigital number, since it uses as much as digits as its factorization.

646520839 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 311040, while the sum is 43.

The square root of 646520839 is about 25426.7740580672. The cubic root of 646520839 is about 864.6908086692.

The spelling of 646520839 in words is "six hundred forty-six million, five hundred twenty thousand, eight hundred thirty-nine".