644144401 has 2 divisors, whose sum is σ = 644144402. Its totient is φ = 644144400.

The previous prime is 644144377. The next prime is 644144411. The reversal of 644144401 is 104441446.

It is a Cunningham number, because it is equal to 25380²+1.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644144400 + 1 = 25380^2 + 1^2 .

It is a cyclic number.

It is not a de Polignac number, because 644144401 - 2¹³ = 644136209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644144401.

It is not a weakly prime, because it can be changed into another prime (644144411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322072200 + 322072201.

It is an arithmetic number, because the mean of its divisors is an integer number (322072201).

Almost surely, 2^644144401 is an apocalyptic number.

It is an amenable number.

644144401 is a deficient number, since it is larger than the sum of its proper divisors (1).

644144401 is an equidigital number, since it uses as much as digits as its factorization.

644144401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6144, while the sum is 28.

The square root of 644144401 is about 25380.0000197006. Note that the first 4 decimals coincide. The cubic root of 644144401 is about 863.6300503966.

Adding to 644144401 its reverse (104441446), we get a palindrome (748585847).

The spelling of 644144401 in words is "six hundred forty-four million, one hundred forty-four thousand, four hundred one".