31143440 has 40 divisors (see below), whose sum is σ = 73441728. Its totient is φ = 12279680.

The previous prime is 31143433. The next prime is 31143443. The reversal of 31143440 is 4434113.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (31143443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2939 + ... + 8421.

Almost surely, 2^31143440 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 31143440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36720864).

31143440 is an abundant number, since it is smaller than the sum of its proper divisors (42298288).

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

31143440 is a wasteful number, since it uses less digits than its factorization.

31143440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5567 (or 5561 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 31143440 is about 5580.6307887191. The cubic root of 31143440 is about 314.6218355966.

Adding to 31143440 its reverse (4434113), we get a palindrome (35577553).

The spelling of 31143440 in words is "thirty-one million, one hundred forty-three thousand, four hundred forty".