64664021 has 2 divisors, whose sum is σ = 64664022. Its totient is φ = 64664020.

The previous prime is 64664003. The next prime is 64664029. The reversal of 64664021 is 12046646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39513796 + 25150225 = 6286^2 + 5015^2 .

It is a cyclic number.

It is not a de Polignac number, because 64664021 - 2¹⁸ = 64401877 is a prime.

It is a super-2 number, since 2×64664021² = 8362871223776882, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64664029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32332010 + 32332011.

It is an arithmetic number, because the mean of its divisors is an integer number (32332011).

Almost surely, 2^64664021 is an apocalyptic number.

It is an amenable number.

64664021 is a deficient number, since it is larger than the sum of its proper divisors (1).

64664021 is an equidigital number, since it uses as much as digits as its factorization.

64664021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 64664021 is about 8041.3942199099. The cubic root of 64664021 is about 401.3786201409.

The spelling of 64664021 in words is "sixty-four million, six hundred sixty-four thousand, twenty-one".