65638981 has 2 divisors, whose sum is σ = 65638982. Its totient is φ = 65638980.

The previous prime is 65638961. The next prime is 65639017. The reversal of 65638981 is 18983656.

65638981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57988225 + 7650756 = 7615^2 + 2766^2 .

It is a cyclic number.

It is not a de Polignac number, because 65638981 - 2⁵ = 65638949 is a prime.

It is a super-2 number, since 2×65638981² = 8616951653436722, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65638961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32819490 + 32819491.

It is an arithmetic number, because the mean of its divisors is an integer number (32819491).

Almost surely, 2^65638981 is an apocalyptic number.

It is an amenable number.

65638981 is a deficient number, since it is larger than the sum of its proper divisors (1).

65638981 is an equidigital number, since it uses as much as digits as its factorization.

65638981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 46.

The square root of 65638981 is about 8101.7887531088. The cubic root of 65638981 is about 403.3858037210.

The spelling of 65638981 in words is "sixty-five million, six hundred thirty-eight thousand, nine hundred eighty-one".