30981 has 8 divisors (see below), whose sum is σ = 43200. Its totient is φ = 19712.

The previous prime is 30977. The next prime is 30983. The reversal of 30981 is 18903.

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 30981 - 2² = 30977 is a prime.

It is a super-2 number, since 2×30981² = 1919644722, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 30981.

It is not an unprimeable number, because it can be changed into a prime (30983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156 + ... + 293.

It is an arithmetic number, because the mean of its divisors is an integer number (5400).

2³⁰⁹⁸¹ is an apocalyptic number.

It is an amenable number.

30981 is a deficient number, since it is larger than the sum of its proper divisors (12219).

30981 is a wasteful number, since it uses less digits than its factorization.

30981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 30981 is about 176.0142039723. The cubic root of 30981 is about 31.4073873378.

The spelling of 30981 in words is "thirty thousand, nine hundred eighty-one".