31221828 has 96 divisors (see below), whose sum is σ = 90599040. Its totient is φ = 9216000.

The previous prime is 31221779. The next prime is 31221847. The reversal of 31221828 is 82812213.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48388 + ... + 49028.

It is an arithmetic number, because the mean of its divisors is an integer number (943740).

Almost surely, 2^31221828 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 31221828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45299520).

31221828 is an abundant number, since it is smaller than the sum of its proper divisors (59377212).

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

31221828 is a wasteful number, since it uses less digits than its factorization.

31221828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706 (or 698 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 31221828 is about 5587.6495953129. The cubic root of 31221828 is about 314.8855820276.

It can be divided in two parts, 3122 and 1828, that added together give a triangular number (4950 = T₉₉).

The spelling of 31221828 in words is "thirty-one million, two hundred twenty-one thousand, eight hundred twenty-eight".