681665233 has 2 divisors, whose sum is σ = 681665234. Its totient is φ = 681665232.

The previous prime is 681665219. The next prime is 681665263. The reversal of 681665233 is 332566186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 666827329 + 14837904 = 25823^2 + 3852^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681665233 is a prime.

It is not a weakly prime, because it can be changed into another prime (681665263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340832616 + 340832617.

It is an arithmetic number, because the mean of its divisors is an integer number (340832617).

Almost surely, 2^681665233 is an apocalyptic number.

It is an amenable number.

681665233 is a deficient number, since it is larger than the sum of its proper divisors (1).

681665233 is an equidigital number, since it uses as much as digits as its factorization.

681665233 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 40.

The square root of 681665233 is about 26108.7194821960. The cubic root of 681665233 is about 880.0831675013.

The spelling of 681665233 in words is "six hundred eighty-one million, six hundred sixty-five thousand, two hundred thirty-three".