64653781 has 2 divisors, whose sum is σ = 64653782. Its totient is φ = 64653780.

The previous prime is 64653779. The next prime is 64653791. The reversal of 64653781 is 18735646.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32832900 + 31820881 = 5730^2 + 5641^2 .

It is a cyclic number.

It is not a de Polignac number, because 64653781 - 2¹ = 64653779 is a prime.

It is a super-2 number, since 2×64653781² = 8360222795191922, which contains 22 as substring.

Together with 64653779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64653791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32326890 + 32326891.

It is an arithmetic number, because the mean of its divisors is an integer number (32326891).

Almost surely, 2^64653781 is an apocalyptic number.

It is an amenable number.

64653781 is a deficient number, since it is larger than the sum of its proper divisors (1).

64653781 is an equidigital number, since it uses as much as digits as its factorization.

64653781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 40.

The square root of 64653781 is about 8040.7574891922. The cubic root of 64653781 is about 401.3574319851.

The spelling of 64653781 in words is "sixty-four million, six hundred fifty-three thousand, seven hundred eighty-one".