31221020 has 48 divisors (see below), whose sum is σ = 67474848. Its totient is φ = 12130560.

The previous prime is 31221017. The next prime is 31221041. The reversal of 31221020 is 2012213.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 31220992 and 31221010.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 191459 + ... + 191621.

It is an arithmetic number, because the mean of its divisors is an integer number (1405726).

Almost surely, 2^31221020 is an apocalyptic number.

It is an amenable number.

31221020 is an abundant number, since it is smaller than the sum of its proper divisors (36253828).

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

31221020 is a wasteful number, since it uses less digits than its factorization.

31221020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 31221020 is about 5587.5772925303. The cubic root of 31221020 is about 314.8828656615.

Adding to 31221020 its reverse (2012213), we get a palindrome (33233233).

The spelling of 31221020 in words is "thirty-one million, two hundred twenty-one thousand, twenty".