331981 has 4 divisors (see below), whose sum is σ = 357532. Its totient is φ = 306432.

The previous prime is 331973. The next prime is 331997. The reversal of 331981 is 189133.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 198025 + 133956 = 445^2 + 366^2 .

It is a cyclic number.

It is not a de Polignac number, because 331981 - 2³ = 331973 is a prime.

It is a super-2 number, since 2×331981² = 220422768722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (331921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12756 + ... + 12781.

It is an arithmetic number, because the mean of its divisors is an integer number (89383).

2³³¹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

331981 is a deficient number, since it is larger than the sum of its proper divisors (25551).

331981 is a wasteful number, since it uses less digits than its factorization.

331981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25550.

The product of its digits is 648, while the sum is 25.

The square root of 331981 is about 576.1779239089. The cubic root of 331981 is about 69.2422347899.

The spelling of 331981 in words is "three hundred thirty-one thousand, nine hundred eighty-one".