691944439 has 2 divisors, whose sum is σ = 691944440. Its totient is φ = 691944438.

The previous prime is 691944431. The next prime is 691944479. The reversal of 691944439 is 934449196.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 691944439 - 2³ = 691944431 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 691944392 and 691944401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691944431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345972219 + 345972220.

It is an arithmetic number, because the mean of its divisors is an integer number (345972220).

Almost surely, 2^691944439 is an apocalyptic number.

691944439 is a deficient number, since it is larger than the sum of its proper divisors (1).

691944439 is an equidigital number, since it uses as much as digits as its factorization.

691944439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 839808, while the sum is 49.

The square root of 691944439 is about 26304.8367985814. The cubic root of 691944439 is about 884.4848690164.

The spelling of 691944439 in words is "six hundred ninety-one million, nine hundred forty-four thousand, four hundred thirty-nine".