31221693 has 20 divisors (see below), whose sum is σ = 49096960. Its totient is φ = 19717992.

The previous prime is 31221667. The next prime is 31221703. The reversal of 31221693 is 39612213.

It is not a de Polignac number, because 31221693 - 2⁹ = 31221181 is a prime.

It is a super-2 number, since 2×31221693² = 1949588227572498, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31221653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 8605 + ... + 11682.

It is an arithmetic number, because the mean of its divisors is an integer number (2454848).

Almost surely, 2^31221693 is an apocalyptic number.

It is an amenable number.

31221693 is a deficient number, since it is larger than the sum of its proper divisors (17875267).

31221693 is a wasteful number, since it uses less digits than its factorization.

31221693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20318 (or 20309 counting only the distinct ones).

The product of its digits is 1944, while the sum is 27.

The square root of 31221693 is about 5587.6375150863. The cubic root of 31221693 is about 314.8851281825.

The spelling of 31221693 in words is "thirty-one million, two hundred twenty-one thousand, six hundred ninety-three".