31121728 has 28 divisors (see below), whose sum is σ = 67372992. Its totient is φ = 14145920.

The previous prime is 31121719. The next prime is 31121729. The reversal of 31121728 is 82712113.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121729) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 21400 + ... + 22807.

Almost surely, 2^31121728 is an apocalyptic number.

It is an amenable number.

31121728 is an abundant number, since it is smaller than the sum of its proper divisors (36251264).

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

31121728 is a wasteful number, since it uses less digits than its factorization.

31121728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44230 (or 44220 counting only the distinct ones).

The product of its digits is 672, while the sum is 25.

The square root of 31121728 is about 5578.6851497463. The cubic root of 31121728 is about 314.5487045471.

The spelling of 31121728 in words is "thirty-one million, one hundred twenty-one thousand, seven hundred twenty-eight".