31323440 has 40 divisors (see below), whose sum is σ = 73337568. Its totient is φ = 12441600.

The previous prime is 31323431. The next prime is 31323449. The reversal of 31323440 is 4432313.

It is an interprime number because it is at equal distance from previous prime (31323431) and next prime (31323449).

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 (31323449) 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, 10784 + ... + 13376.

Almost surely, 2^31323440 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 31323440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36668784).

31323440 is an abundant number, since it is smaller than the sum of its proper divisors (42014128).

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

31323440 is a wasteful number, since it uses less digits than its factorization.

31323440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2757 (or 2751 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 20.

The square root of 31323440 is about 5596.7347623413. The cubic root of 31323440 is about 315.2268123755.

Adding to 31323440 its reverse (4432313), we get a palindrome (35755753).

The spelling of 31323440 in words is "thirty-one million, three hundred twenty-three thousand, four hundred forty".