691038391 has 8 divisors (see below), whose sum is σ = 716179968. Its totient is φ = 666075000.

The previous prime is 691038377. The next prime is 691038401. The reversal of 691038391 is 193830196.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 691038391 - 2²³ = 682649783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691038301) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36625 + ... + 52186.

It is an arithmetic number, because the mean of its divisors is an integer number (89522496).

Almost surely, 2^691038391 is an apocalyptic number.

691038391 is a deficient number, since it is larger than the sum of its proper divisors (25141577).

691038391 is a wasteful number, since it uses less digits than its factorization.

691038391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89093.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 691038391 is about 26287.6090772820. The cubic root of 691038391 is about 884.0986454314.

The spelling of 691038391 in words is "six hundred ninety-one million, thirty-eight thousand, three hundred ninety-one".