644051 has 2 divisors, whose sum is σ = 644052. Its totient is φ = 644050.

The previous prime is 644047. The next prime is 644053. The reversal of 644051 is 150446.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644051 - 2² = 644047 is a prime.

It is a Sophie Germain prime.

Together with 644053, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p₅₂₃₆₄ and since 644051 and 52364 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (644053) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322025 + 322026.

It is an arithmetic number, because the mean of its divisors is an integer number (322026).

2⁶⁴⁴⁰⁵¹ is an apocalyptic number.

644051 is a deficient number, since it is larger than the sum of its proper divisors (1).

644051 is an equidigital number, since it uses as much as digits as its factorization.

644051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 644051 is about 802.5278811356. The cubic root of 644051 is about 86.3588306232.

Adding to 644051 its reverse (150446), we get a palindrome (794497).

The spelling of 644051 in words is "six hundred forty-four thousand, fifty-one".