644420413 has 12 divisors (see below), whose sum is σ = 807296700. Its totient is φ = 509870592.

The previous prime is 644420401. The next prime is 644420419. The reversal of 644420413 is 314024446.

644420413 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 346443769 + 297976644 = 18613^2 + 17262^2 .

It is a de Polignac number, because none of the positive numbers 2^k-644420413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644420419) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 505188 + ... + 506461.

It is an arithmetic number, because the mean of its divisors is an integer number (67274725).

Almost surely, 2^644420413 is an apocalyptic number.

It is an amenable number.

644420413 is a deficient number, since it is larger than the sum of its proper divisors (162876287).

644420413 is a wasteful number, since it uses less digits than its factorization.

644420413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1011676 (or 1011669 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 644420413 is about 25385.4370259801. The cubic root of 644420413 is about 863.7533862087.

Adding to 644420413 its reverse (314024446), we get a palindrome (958444859).

The spelling of 644420413 in words is "six hundred forty-four million, four hundred twenty thousand, four hundred thirteen".