315991 has 8 divisors (see below), whose sum is σ = 344960. Its totient is φ = 287712.

The previous prime is 315977. The next prime is 316003. The reversal of 315991 is 199513.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-315991 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 (315961) 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, 1306 + ... + 1528.

It is an arithmetic number, because the mean of its divisors is an integer number (43120).

2³¹⁵⁹⁹¹ is an apocalyptic number.

315991 is a deficient number, since it is larger than the sum of its proper divisors (28969).

315991 is a wasteful number, since it uses less digits than its factorization.

315991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345.

The product of its digits is 1215, while the sum is 28.

The square root of 315991 is about 562.1307677045. The cubic root of 315991 is about 68.1121994298.

Adding to 315991 its product of digits (1215), we get a triangular number (317206 = T₇₉₆).

The spelling of 315991 in words is "three hundred fifteen thousand, nine hundred ninety-one".