31323240 has 256 divisors, whose sum is σ = 118540800. Its totient is φ = 7299072.

The previous prime is 31323223. The next prime is 31323251. The reversal of 31323240 is 4232313.

It is a super-2 number, since 2×31323240² = 1962290728195200, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 322872 + ... + 322968.

It is an arithmetic number, because the mean of its divisors is an integer number (463050).

Almost surely, 2^31323240 is an apocalyptic number.

31323240 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 31323240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59270400).

31323240 is an abundant number, since it is smaller than the sum of its proper divisors (87217560).

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

31323240 is a wasteful number, since it uses less digits than its factorization.

31323240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153 (or 143 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 18.

The square root of 31323240 is about 5596.7168947518. The cubic root of 31323240 is about 315.2261414669.

Adding to 31323240 its reverse (4232313), we get a palindrome (35555553).

The spelling of 31323240 in words is "thirty-one million, three hundred twenty-three thousand, two hundred forty".