309691 has 8 divisors (see below), whose sum is σ = 327600. Its totient is φ = 292320.

The previous prime is 309677. The next prime is 309707. The reversal of 309691 is 196903.

309691 = 89² + 90² + ... + 117².

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-309691 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 (309671) 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, 1621 + ... + 1801.

It is an arithmetic number, because the mean of its divisors is an integer number (40950).

2³⁰⁹⁶⁹¹ is an apocalyptic number.

309691 is a deficient number, since it is larger than the sum of its proper divisors (17909).

309691 is a wasteful number, since it uses less digits than its factorization.

309691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 309691 is about 556.4988769081. The cubic root of 309691 is about 67.6565001538.

It can be divided in two parts, 309 and 691, that added together give a cube (1000 = 10³).

The spelling of 309691 in words is "three hundred nine thousand, six hundred ninety-one".