691919 has 2 divisors, whose sum is σ = 691920. Its totient is φ = 691918.

The previous prime is 691907. The next prime is 691921. The reversal of 691919 is 919196.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691919 - 2⁴ = 691903 is a prime.

It is a super-2 number, since 2×691919² = 957503805122, which contains 22 as substring.

Together with 691921, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345959 + 345960.

It is an arithmetic number, because the mean of its divisors is an integer number (345960).

2⁶⁹¹⁹¹⁹ is an apocalyptic number.

691919 is a deficient number, since it is larger than the sum of its proper divisors (1).

691919 is an equidigital number, since it uses as much as digits as its factorization.

691919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4374, while the sum is 35.

The square root of 691919 is about 831.8166865362. The cubic root of 691919 is about 88.4474029665.

The spelling of 691919 in words is "six hundred ninety-one thousand, nine hundred nineteen".