691393739 has 2 divisors, whose sum is σ = 691393740. Its totient is φ = 691393738.

The previous prime is 691393711. The next prime is 691393789. The reversal of 691393739 is 937393196.

It is a happy number.

It is an a-pointer prime, because the next prime (691393789) can be obtained adding 691393739 to its sum of digits (50).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691393739 is a prime.

It is not a weakly prime, because it can be changed into another prime (691393709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345696869 + 345696870.

It is an arithmetic number, because the mean of its divisors is an integer number (345696870).

Almost surely, 2^691393739 is an apocalyptic number.

691393739 is a deficient number, since it is larger than the sum of its proper divisors (1).

691393739 is an equidigital number, since it uses as much as digits as its factorization.

691393739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 826686, while the sum is 50.

The square root of 691393739 is about 26294.3670583644. The cubic root of 691393739 is about 884.2501608199.

The spelling of 691393739 in words is "six hundred ninety-one million, three hundred ninety-three thousand, seven hundred thirty-nine".