691598391 has 8 divisors (see below), whose sum is σ = 1005961344. Its totient is φ = 419150520.

The previous prime is 691598381. The next prime is 691598393. The reversal of 691598391 is 193895196.

It is a happy number.

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

It is not a de Polignac number, because 691598391 - 2⁵ = 691598359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691598393) 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, 10478731 + ... + 10478796.

It is an arithmetic number, because the mean of its divisors is an integer number (125745168).

Almost surely, 2^691598391 is an apocalyptic number.

691598391 is a deficient number, since it is larger than the sum of its proper divisors (314362953).

691598391 is a wasteful number, since it uses less digits than its factorization.

691598391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20957541.

The product of its digits is 524880, while the sum is 51.

The square root of 691598391 is about 26298.2583263607. The cubic root of 691598391 is about 884.3373979959.

The spelling of 691598391 in words is "six hundred ninety-one million, five hundred ninety-eight thousand, three hundred ninety-one".