644377441 has 2 divisors, whose sum is σ = 644377442. Its totient is φ = 644377440.

The previous prime is 644377427. The next prime is 644377463. The reversal of 644377441 is 144773446.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 580617216 + 63760225 = 24096^2 + 7985^2 .

It is a cyclic number.

It is not a de Polignac number, because 644377441 - 2¹⁹ = 643853153 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644377394 and 644377403.

It is not a weakly prime, because it can be changed into another prime (644377421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322188720 + 322188721.

It is an arithmetic number, because the mean of its divisors is an integer number (322188721).

Almost surely, 2^644377441 is an apocalyptic number.

It is an amenable number.

644377441 is a deficient number, since it is larger than the sum of its proper divisors (1).

644377441 is an equidigital number, since it uses as much as digits as its factorization.

644377441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 40.

The square root of 644377441 is about 25384.5906210835. The cubic root of 644377441 is about 863.7341865088.

The spelling of 644377441 in words is "six hundred forty-four million, three hundred seventy-seven thousand, four hundred forty-one".