31221424 has 40 divisors (see below), whose sum is σ = 65481920. Its totient is φ = 14335488.

The previous prime is 31221413. The next prime is 31221431. The reversal of 31221424 is 42412213.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 76132 + ... + 76540.

It is an arithmetic number, because the mean of its divisors is an integer number (1637048).

Almost surely, 2^31221424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31221424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32740960).

31221424 is an abundant number, since it is smaller than the sum of its proper divisors (34260496).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31221424 is a wasteful number, since it uses less digits than its factorization.

31221424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 797 (or 791 counting only the distinct ones).

The product of its digits is 384, while the sum is 19.

The square root of 31221424 is about 5587.6134440385. The cubic root of 31221424 is about 314.8842238504.

Adding to 31221424 its reverse (42412213), we get a palindrome (73633637).

It can be divided in two parts, 312 and 21424, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 31221424 in words is "thirty-one million, two hundred twenty-one thousand, four hundred twenty-four".