644570513 has 2 divisors, whose sum is σ = 644570514. Its totient is φ = 644570512.

The previous prime is 644570489. The next prime is 644570527. The reversal of 644570513 is 315075446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 497869969 + 146700544 = 22313^2 + 12112^2 .

It is a cyclic number.

It is not a de Polignac number, because 644570513 - 2⁶ = 644570449 is a prime.

It is a super-2 number, since 2×644570513² = 830942292458166338, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644500513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322285256 + 322285257.

It is an arithmetic number, because the mean of its divisors is an integer number (322285257).

Almost surely, 2^644570513 is an apocalyptic number.

It is an amenable number.

644570513 is a deficient number, since it is larger than the sum of its proper divisors (1).

644570513 is an equidigital number, since it uses as much as digits as its factorization.

644570513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50400, while the sum is 35.

The square root of 644570513 is about 25388.3932733050. The cubic root of 644570513 is about 863.8204435292.

The spelling of 644570513 in words is "six hundred forty-four million, five hundred seventy thousand, five hundred thirteen".