644426029957 has 2 divisors, whose sum is σ = 644426029958. Its totient is φ = 644426029956.

The previous prime is 644426029879. The next prime is 644426029991. The reversal of 644426029957 is 759920624446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 616309782916 + 28116247041 = 785054^2 + 167679^2 .

It is a cyclic number.

It is not a de Polignac number, because 644426029957 - 2⁷ = 644426029829 is a prime.

It is a super-2 number, since 2×644426029957² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644426029997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322213014978 + 322213014979.

It is an arithmetic number, because the mean of its divisors is an integer number (322213014979).

Almost surely, 2^644426029957 is an apocalyptic number.

It is an amenable number.

644426029957 is a deficient number, since it is larger than the sum of its proper divisors (1).

644426029957 is an equidigital number, since it uses as much as digits as its factorization.

644426029957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26127360, while the sum is 58.

The spelling of 644426029957 in words is "six hundred forty-four billion, four hundred twenty-six million, twenty-nine thousand, nine hundred fifty-seven".