644528706551 has 2 divisors, whose sum is σ = 644528706552. Its totient is φ = 644528706550.

The previous prime is 644528706539. The next prime is 644528706553. The reversal of 644528706551 is 155607825446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644528706551 - 2¹⁸ = 644528444407 is a prime.

Together with 644528706553, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 644528706493 and 644528706502.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644528706553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322264353275 + 322264353276.

It is an arithmetic number, because the mean of its divisors is an integer number (322264353276).

Almost surely, 2^644528706551 is an apocalyptic number.

644528706551 is a deficient number, since it is larger than the sum of its proper divisors (1).

644528706551 is an equidigital number, since it uses as much as digits as its factorization.

644528706551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064000, while the sum is 53.

The spelling of 644528706551 in words is "six hundred forty-four billion, five hundred twenty-eight million, seven hundred six thousand, five hundred fifty-one".