31228821 has 40 divisors (see below), whose sum is σ = 51389184. Its totient is φ = 18779040.

The previous prime is 31228817. The next prime is 31228823. The reversal of 31228821 is 12882213.

It is not a de Polignac number, because 31228821 - 2² = 31228817 is a prime.

It is a super-2 number, since 2×31228821² = 1950478522100082, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31228823) 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 39 ways as a sum of consecutive naturals, for example, 49176 + ... + 49806.

Almost surely, 2^31228821 is an apocalyptic number.

It is an amenable number.

31228821 is a deficient number, since it is larger than the sum of its proper divisors (20160363).

31228821 is a wasteful number, since it uses less digits than its factorization.

31228821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 703 (or 694 counting only the distinct ones).

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

The square root of 31228821 is about 5588.2753153366. The cubic root of 31228821 is about 314.9090894115.

The spelling of 31228821 in words is "thirty-one million, two hundred twenty-eight thousand, eight hundred twenty-one".