64638661 has 2 divisors, whose sum is σ = 64638662. Its totient is φ = 64638660.

The previous prime is 64638659. The next prime is 64638697. The reversal of 64638661 is 16683646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62964225 + 1674436 = 7935^2 + 1294^2 .

It is a cyclic number.

It is not a de Polignac number, because 64638661 - 2¹ = 64638659 is a prime.

Together with 64638659, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64638601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32319330 + 32319331.

It is an arithmetic number, because the mean of its divisors is an integer number (32319331).

Almost surely, 2^64638661 is an apocalyptic number.

It is an amenable number.

64638661 is a deficient number, since it is larger than the sum of its proper divisors (1).

64638661 is an equidigital number, since it uses as much as digits as its factorization.

64638661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 40.

The square root of 64638661 is about 8039.8172242906. The cubic root of 64638661 is about 401.3261422580.

The spelling of 64638661 in words is "sixty-four million, six hundred thirty-eight thousand, six hundred sixty-one".