691726813 has 2 divisors, whose sum is σ = 691726814. Its totient is φ = 691726812.

The previous prime is 691726807. The next prime is 691726823. The reversal of 691726813 is 318627196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 492973209 + 198753604 = 22203^2 + 14098^2 .

It is a cyclic number.

It is not a de Polignac number, because 691726813 - 2²⁵ = 658172381 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 691726813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691726823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345863406 + 345863407.

It is an arithmetic number, because the mean of its divisors is an integer number (345863407).

Almost surely, 2^691726813 is an apocalyptic number.

It is an amenable number.

691726813 is a deficient number, since it is larger than the sum of its proper divisors (1).

691726813 is an equidigital number, since it uses as much as digits as its factorization.

691726813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The square root of 691726813 is about 26300.6998576084. The cubic root of 691726813 is about 884.3921317595.

The spelling of 691726813 in words is "six hundred ninety-one million, seven hundred twenty-six thousand, eight hundred thirteen".