31820040 has 320 divisors, whose sum is σ = 129634560. Its totient is φ = 6842880.

The previous prime is 31820029. The next prime is 31820051. The reversal of 31820040 is 4002813.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (31820029) and next prime (31820051).

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

It is a junction number, because it is equal to n+sod(n) for n = 31819995 and 31820022.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 521610 + ... + 521670.

It is an arithmetic number, because the mean of its divisors is an integer number (405108).

Almost surely, 2^31820040 is an apocalyptic number.

31820040 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 31820040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (64817280).

31820040 is an abundant number, since it is smaller than the sum of its proper divisors (97814520).

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

31820040 is a wasteful number, since it uses less digits than its factorization.

31820040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 101 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 31820040 is about 5640.9254559868. The cubic root of 31820040 is about 316.8839481385.

Adding to 31820040 its reverse (4002813), we get a palindrome (35822853).

The spelling of 31820040 in words is "thirty-one million, eight hundred twenty thousand, forty".