640451323639 has 2 divisors, whose sum is σ = 640451323640. Its totient is φ = 640451323638.

The previous prime is 640451323613. The next prime is 640451323661. The reversal of 640451323639 is 936323154046.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640451323639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640451323669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320225661819 + 320225661820.

It is an arithmetic number, because the mean of its divisors is an integer number (320225661820).

Almost surely, 2^640451323639 is an apocalyptic number.

640451323639 is a deficient number, since it is larger than the sum of its proper divisors (1).

640451323639 is an equidigital number, since it uses as much as digits as its factorization.

640451323639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1399680, while the sum is 46.

It can be divided in two parts, 64045 and 1323639, that added together give a square (1387684 = 1178²).

The spelling of 640451323639 in words is "six hundred forty billion, four hundred fifty-one million, three hundred twenty-three thousand, six hundred thirty-nine".