691325221 has 4 divisors (see below), whose sum is σ = 691455744. Its totient is φ = 691194700.

The previous prime is 691325161. The next prime is 691325227. The reversal of 691325221 is 122523196.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691325221 is a prime.

It is a super-2 number, since 2×691325221² = 955861122381397682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691325227) 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 in 3 ways as a sum of consecutive naturals, for example, 56965 + ... + 68026.

It is an arithmetic number, because the mean of its divisors is an integer number (172863936).

Almost surely, 2^691325221 is an apocalyptic number.

It is an amenable number.

691325221 is a deficient number, since it is larger than the sum of its proper divisors (130523).

691325221 is a wasteful number, since it uses less digits than its factorization.

691325221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130522.

The product of its digits is 6480, while the sum is 31.

The square root of 691325221 is about 26293.0641234528. The cubic root of 691325221 is about 884.2209497493.

The spelling of 691325221 in words is "six hundred ninety-one million, three hundred twenty-five thousand, two hundred twenty-one".