691708439 has 2 divisors, whose sum is σ = 691708440. Its totient is φ = 691708438.

The previous prime is 691708397. The next prime is 691708477. The reversal of 691708439 is 934807196.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691708439 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 691708393 and 691708402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691708639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345854219 + 345854220.

It is an arithmetic number, because the mean of its divisors is an integer number (345854220).

Almost surely, 2^691708439 is an apocalyptic number.

691708439 is a deficient number, since it is larger than the sum of its proper divisors (1).

691708439 is an equidigital number, since it uses as much as digits as its factorization.

691708439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 47.

The square root of 691708439 is about 26300.3505489946. The cubic root of 691708439 is about 884.3843011321.

The spelling of 691708439 in words is "six hundred ninety-one million, seven hundred eight thousand, four hundred thirty-nine".