64644440626621 has 2 divisors, whose sum is σ = 64644440626622. Its totient is φ = 64644440626620.

The previous prime is 64644440626609. The next prime is 64644440626651. The reversal of 64644440626621 is 12662604444646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 33208077396025 + 31436363230596 = 5762645^2 + 5606814^2 .

It is a cyclic number.

It is not a de Polignac number, because 64644440626621 - 2²¹ = 64644438529469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64644440626651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32322220313310 + 32322220313311.

It is an arithmetic number, because the mean of its divisors is an integer number (32322220313311).

Almost surely, 2^{64644440626621} is an apocalyptic number.

It is an amenable number.

64644440626621 is a deficient number, since it is larger than the sum of its proper divisors (1).

64644440626621 is an equidigital number, since it uses as much as digits as its factorization.

64644440626621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31850496, while the sum is 55.

The spelling of 64644440626621 in words is "sixty-four trillion, six hundred forty-four billion, four hundred forty million, six hundred twenty-six thousand, six hundred twenty-one".