644401211 has 2 divisors, whose sum is σ = 644401212. Its totient is φ = 644401210.

The previous prime is 644401181. The next prime is 644401229. The reversal of 644401211 is 112104446.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644401211 - 2²⁶ = 577292347 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644401271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322200605 + 322200606.

It is an arithmetic number, because the mean of its divisors is an integer number (322200606).

Almost surely, 2^644401211 is an apocalyptic number.

644401211 is a deficient number, since it is larger than the sum of its proper divisors (1).

644401211 is an equidigital number, since it uses as much as digits as its factorization.

644401211 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 644401211 is about 25385.0588141923. The cubic root of 644401211 is about 863.7448069454.

Adding to 644401211 its reverse (112104446), we get a palindrome (756505657).

The spelling of 644401211 in words is "six hundred forty-four million, four hundred one thousand, two hundred eleven".