681261869 has 2 divisors, whose sum is σ = 681261870. Its totient is φ = 681261868.

The previous prime is 681261839. The next prime is 681261887. The reversal of 681261869 is 968162186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 417589225 + 263672644 = 20435^2 + 16238^2 .

It is a cyclic number.

It is not a de Polignac number, because 681261869 - 2²⁸ = 412826413 is a prime.

It is a super-2 number, since 2×681261869² = 928235468306746322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681261809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340630934 + 340630935.

It is an arithmetic number, because the mean of its divisors is an integer number (340630935).

Almost surely, 2^681261869 is an apocalyptic number.

It is an amenable number.

681261869 is a deficient number, since it is larger than the sum of its proper divisors (1).

681261869 is an equidigital number, since it uses as much as digits as its factorization.

681261869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 47.

The square root of 681261869 is about 26100.9936400896. The cubic root of 681261869 is about 879.9095417521.

The spelling of 681261869 in words is "six hundred eighty-one million, two hundred sixty-one thousand, eight hundred sixty-nine".