31998240 has 144 divisors (see below), whose sum is σ = 113375808. Its totient is φ = 8522496.

The previous prime is 31998227. The next prime is 31998277. The reversal of 31998240 is 4289913.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 31998195 and 31998204.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38469 + ... + 39291.

It is an arithmetic number, because the mean of its divisors is an integer number (787332).

Almost surely, 2^31998240 is an apocalyptic number.

31998240 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 31998240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56687904).

31998240 is an abundant number, since it is smaller than the sum of its proper divisors (81377568).

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

31998240 is an equidigital number, since it uses as much as digits as its factorization.

31998240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853 (or 833 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 31998240 is about 5656.6986838615. The cubic root of 31998240 is about 317.4743898164.

The spelling of 31998240 in words is "thirty-one million, nine hundred ninety-eight thousand, two hundred forty".