65011981 has 2 divisors, whose sum is σ = 65011982. Its totient is φ = 65011980.

The previous prime is 65011963. The next prime is 65012021. The reversal of 65011981 is 18911056.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58277956 + 6734025 = 7634^2 + 2595^2 .

It is a cyclic number.

It is not a de Polignac number, because 65011981 - 2⁷ = 65011853 is a prime.

It is a super-2 number, since 2×65011981² = 8453115347088722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65011081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32505990 + 32505991.

It is an arithmetic number, because the mean of its divisors is an integer number (32505991).

Almost surely, 2^65011981 is an apocalyptic number.

It is an amenable number.

65011981 is a deficient number, since it is larger than the sum of its proper divisors (1).

65011981 is an equidigital number, since it uses as much as digits as its factorization.

65011981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 65011981 is about 8063.0007441399. Note that the first 3 decimals coincide. The cubic root of 65011981 is about 402.0972780927.

The spelling of 65011981 in words is "sixty-five million, eleven thousand, nine hundred eighty-one".