646624609 has 2 divisors, whose sum is σ = 646624610. Its totient is φ = 646624608.

The previous prime is 646624577. The next prime is 646624633. The reversal of 646624609 is 906426646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 616429584 + 30195025 = 24828^2 + 5495^2 .

It is a cyclic number.

It is not a de Polignac number, because 646624609 - 2⁵ = 646624577 is a prime.

It is not a weakly prime, because it can be changed into another prime (646627609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323312304 + 323312305.

It is an arithmetic number, because the mean of its divisors is an integer number (323312305).

Almost surely, 2^646624609 is an apocalyptic number.

It is an amenable number.

646624609 is a deficient number, since it is larger than the sum of its proper divisors (1).

646624609 is an equidigital number, since it uses as much as digits as its factorization.

646624609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 373248, while the sum is 43.

The square root of 646624609 is about 25428.8145417752. The cubic root of 646624609 is about 864.7370686707.

The spelling of 646624609 in words is "six hundred forty-six million, six hundred twenty-four thousand, six hundred nine".