64637561 has 2 divisors, whose sum is σ = 64637562. Its totient is φ = 64637560.

The previous prime is 64637533. The next prime is 64637579. The reversal of 64637561 is 16573646.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61465600 + 3171961 = 7840^2 + 1781^2 .

It is a cyclic number.

It is not a de Polignac number, because 64637561 - 2¹⁴ = 64621177 is a prime.

It is not a weakly prime, because it can be changed into another prime (64637861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32318780 + 32318781.

It is an arithmetic number, because the mean of its divisors is an integer number (32318781).

Almost surely, 2^64637561 is an apocalyptic number.

It is an amenable number.

64637561 is a deficient number, since it is larger than the sum of its proper divisors (1).

64637561 is an equidigital number, since it uses as much as digits as its factorization.

64637561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 38.

The square root of 64637561 is about 8039.7488144842. The cubic root of 64637561 is about 401.3238656985.

The spelling of 64637561 in words is "sixty-four million, six hundred thirty-seven thousand, five hundred sixty-one".