31323220 has 24 divisors (see below), whose sum is σ = 65948904. Its totient is φ = 12496896.

The previous prime is 31323203. The next prime is 31323223. The reversal of 31323220 is 2232313.

It can be written as a sum of positive squares in 4 ways, for example, as 2033476 + 29289744 = 1426^2 + 5412^2 .

It is a super-2 number, since 2×31323220² = 1962288222336800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 31323194 and 31323203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31323223) 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, 6852 + ... + 10468.

It is an arithmetic number, because the mean of its divisors is an integer number (2747871).

Almost surely, 2^31323220 is an apocalyptic number.

It is an amenable number.

31323220 is an abundant number, since it is smaller than the sum of its proper divisors (34625684).

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

31323220 is a wasteful number, since it uses less digits than its factorization.

31323220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4059 (or 4057 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 16.

The square root of 31323220 is about 5596.7151079897. The cubic root of 31323220 is about 315.2260743759.

Adding to 31323220 its reverse (2232313), we get a palindrome (33555533).

The spelling of 31323220 in words is "thirty-one million, three hundred twenty-three thousand, two hundred twenty".