31440220 has 48 divisors (see below), whose sum is σ = 76543488. Its totient is φ = 10624320.

The previous prime is 31440217. The next prime is 31440221. The reversal of 31440220 is 2204413.

It is a junction number, because it is equal to n+sod(n) for n = 31440194 and 31440203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31440221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8359 + ... + 11521.

It is an arithmetic number, because the mean of its divisors is an integer number (1594656).

Almost surely, 2^31440220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31440220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38271744).

31440220 is an abundant number, since it is smaller than the sum of its proper divisors (45103268).

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

31440220 is a wasteful number, since it uses less digits than its factorization.

31440220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3250 (or 3248 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 31440220 is about 5607.1579253665. The cubic root of 31440220 is about 315.6180692528.

Adding to 31440220 its reverse (2204413), we get a palindrome (33644633).

The spelling of 31440220 in words is "thirty-one million, four hundred forty thousand, two hundred twenty".