644722031 has 2 divisors, whose sum is σ = 644722032. Its totient is φ = 644722030.

The previous prime is 644722027. The next prime is 644722049. The reversal of 644722031 is 130227446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644722031 - 2² = 644722027 is a prime.

It is a super-2 number, since 2×644722031² = 831332994513529922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 644721985 and 644722003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644742031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322361015 + 322361016.

It is an arithmetic number, because the mean of its divisors is an integer number (322361016).

Almost surely, 2^644722031 is an apocalyptic number.

644722031 is a deficient number, since it is larger than the sum of its proper divisors (1).

644722031 is an equidigital number, since it uses as much as digits as its factorization.

644722031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 29.

The square root of 644722031 is about 25391.3770993225. The cubic root of 644722031 is about 863.8881237851. Note that the first 3 decimals are identical.

Adding to 644722031 its reverse (130227446), we get a palindrome (774949477).

The spelling of 644722031 in words is "six hundred forty-four million, seven hundred twenty-two thousand, thirty-one".