31242420 has 144 divisors (see below), whose sum is σ = 106928640. Its totient is φ = 7315200.

The previous prime is 31242397. The next prime is 31242433. The reversal of 31242420 is 2424213.

31242420 is a `hidden beast` number, since 3 + 1 + 242 + 420 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31242393 and 31242402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 61126 + ... + 61634.

It is an arithmetic number, because the mean of its divisors is an integer number (742560).

Almost surely, 2^31242420 is an apocalyptic number.

31242420 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 31242420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53464320).

31242420 is an abundant number, since it is smaller than the sum of its proper divisors (75686220).

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

31242420 is a wasteful number, since it uses less digits than its factorization.

31242420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566 (or 561 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 31242420 is about 5589.4919268213. The cubic root of 31242420 is about 314.9547932102.

Adding to 31242420 its reverse (2424213), we get a palindrome (33666633).

The spelling of 31242420 in words is "thirty-one million, two hundred forty-two thousand, four hundred twenty".