31128240 has 160 divisors (see below), whose sum is σ = 113492736. Its totient is φ = 6958080.

The previous prime is 31128221. The next prime is 31128257. The reversal of 31128240 is 4282113.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33867 + ... + 34773.

Almost surely, 2^31128240 is an apocalyptic number.

31128240 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31128240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56746368).

31128240 is an abundant number, since it is smaller than the sum of its proper divisors (82364496).

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

31128240 is a wasteful number, since it uses less digits than its factorization.

31128240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 947 (or 941 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 31128240 is about 5579.2687692923. The cubic root of 31128240 is about 314.5706420427.

It can be divided in two parts, 31 and 128240, that added together give a triangular number (128271 = T₅₀₆).

The spelling of 31128240 in words is "thirty-one million, one hundred twenty-eight thousand, two hundred forty".