644646433016123 has 2 divisors, whose sum is σ = 644646433016124. Its totient is φ = 644646433016122.

The previous prime is 644646433016119. The next prime is 644646433016177. The reversal of 644646433016123 is 321610334646446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644646433016123 - 2² = 644646433016119 is a prime.

It is a super-2 number, since 2×644646433016123² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (644646433016623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322323216508061 + 322323216508062.

It is an arithmetic number, because the mean of its divisors is an integer number (322323216508062).

Almost surely, 2^{644646433016123} is an apocalyptic number.

644646433016123 is a deficient number, since it is larger than the sum of its proper divisors (1).

644646433016123 is an equidigital number, since it uses as much as digits as its factorization.

644646433016123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17915904, while the sum is 53.

The spelling of 644646433016123 in words is "six hundred forty-four trillion, six hundred forty-six billion, four hundred thirty-three million, sixteen thousand, one hundred twenty-three".