31021380 has 144 divisors (see below), whose sum is σ = 105303744. Its totient is φ = 7620480.

The previous prime is 31021373. The next prime is 31021399. The reversal of 31021380 is 8312013.

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

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, 62935 + ... + 63425.

It is an arithmetic number, because the mean of its divisors is an integer number (731276).

Almost surely, 2^31021380 is an apocalyptic number.

31021380 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 31021380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52651872).

31021380 is an abundant number, since it is smaller than the sum of its proper divisors (74282364).

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

31021380 is a wasteful number, since it uses less digits than its factorization.

31021380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528 (or 514 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 31021380 is about 5569.6840125810. The cubic root of 31021380 is about 314.2102666198.

Adding to 31021380 its reverse (8312013), we get a palindrome (39333393).

The spelling of 31021380 in words is "thirty-one million, twenty-one thousand, three hundred eighty".