691479251 has 2 divisors, whose sum is σ = 691479252. Its totient is φ = 691479250.

The previous prime is 691479247. The next prime is 691479253. The reversal of 691479251 is 152974196.

691479251 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691479251 - 2² = 691479247 is a prime.

It is a super-4 number, since 4×691479251⁴ (a number of 36 digits) contains 4444 as substring.

Together with 691479253, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (691479253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345739625 + 345739626.

It is an arithmetic number, because the mean of its divisors is an integer number (345739626).

Almost surely, 2^691479251 is an apocalyptic number.

691479251 is a deficient number, since it is larger than the sum of its proper divisors (1).

691479251 is an equidigital number, since it uses as much as digits as its factorization.

691479251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 44.

The square root of 691479251 is about 26295.9930597800. The cubic root of 691479251 is about 884.2866141838.

The spelling of 691479251 in words is "six hundred ninety-one million, four hundred seventy-nine thousand, two hundred fifty-one".