31221040 has 20 divisors (see below), whose sum is σ = 72589104. Its totient is φ = 12488384.

The previous prime is 31221017. The next prime is 31221041. The reversal of 31221040 is 4012213.

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 31221040.

It is not an unprimeable number, because it can be changed into a prime (31221041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 195052 + ... + 195211.

Almost surely, 2^31221040 is an apocalyptic number.

It is an amenable number.

31221040 is an abundant number, since it is smaller than the sum of its proper divisors (41368064).

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

31221040 is a wasteful number, since it uses less digits than its factorization.

31221040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390276 (or 390270 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 31221040 is about 5587.5790822144. The cubic root of 31221040 is about 314.8829328988.

Adding to 31221040 its reverse (4012213), we get a palindrome (35233253).

The spelling of 31221040 in words is "thirty-one million, two hundred twenty-one thousand, forty".