64642662521 has 2 divisors, whose sum is σ = 64642662522. Its totient is φ = 64642662520.

The previous prime is 64642662479. The next prime is 64642662527. The reversal of 64642662521 is 12526624646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49522271296 + 15120391225 = 222536^2 + 122965^2 .

It is a cyclic number.

It is not a de Polignac number, because 64642662521 - 2⁶ = 64642662457 is a prime.

It is not a weakly prime, because it can be changed into another prime (64642662527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32321331260 + 32321331261.

It is an arithmetic number, because the mean of its divisors is an integer number (32321331261).

Almost surely, 2^64642662521 is an apocalyptic number.

It is an amenable number.

64642662521 is a deficient number, since it is larger than the sum of its proper divisors (1).

64642662521 is an equidigital number, since it uses as much as digits as its factorization.

64642662521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 829440, while the sum is 44.

The spelling of 64642662521 in words is "sixty-four billion, six hundred forty-two million, six hundred sixty-two thousand, five hundred twenty-one".