31722981 has 4 divisors (see below), whose sum is σ = 42297312. Its totient is φ = 21148652.

The previous prime is 31722973. The next prime is 31722983. The reversal of 31722981 is 18922713.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18922713 = 3 ⋅6307571.

It is a cyclic number.

It is not a de Polignac number, because 31722981 - 2³ = 31722973 is a prime.

It is a super-2 number, since 2×31722981² = 2012695047052722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31722983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5287161 + ... + 5287166.

It is an arithmetic number, because the mean of its divisors is an integer number (10574328).

Almost surely, 2^31722981 is an apocalyptic number.

It is an amenable number.

31722981 is a deficient number, since it is larger than the sum of its proper divisors (10574331).

31722981 is a wasteful number, since it uses less digits than its factorization.

31722981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10574330.

The product of its digits is 6048, while the sum is 33.

The square root of 31722981 is about 5632.3157759486. The cubic root of 31722981 is about 316.5614284956.

The spelling of 31722981 in words is "thirty-one million, seven hundred twenty-two thousand, nine hundred eighty-one".