644124451 has 2 divisors, whose sum is σ = 644124452. Its totient is φ = 644124450.

The previous prime is 644124449. The next prime is 644124457. The reversal of 644124451 is 154421446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644124451 - 2¹ = 644124449 is a prime.

Together with 644124449, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (644124457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322062225 + 322062226.

It is an arithmetic number, because the mean of its divisors is an integer number (322062226).

Almost surely, 2^644124451 is an apocalyptic number.

644124451 is a deficient number, since it is larger than the sum of its proper divisors (1).

644124451 is an equidigital number, since it uses as much as digits as its factorization.

644124451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15360, while the sum is 31.

The square root of 644124451 is about 25379.6069906529. The cubic root of 644124451 is about 863.6211343847.

Adding to 644124451 its reverse (154421446), we get a palindrome (798545897).

The spelling of 644124451 in words is "six hundred forty-four million, one hundred twenty-four thousand, four hundred fifty-one".