31223540 has 24 divisors (see below), whose sum is σ = 65917320. Its totient is φ = 12423168.

The previous prime is 31223539. The next prime is 31223551. The reversal of 31223540 is 4532213.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 708964 + 30514576 = 842^2 + 5524^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185 + ... + 7904.

It is an arithmetic number, because the mean of its divisors is an integer number (2746555).

Almost surely, 2^31223540 is an apocalyptic number.

It is an amenable number.

31223540 is an abundant number, since it is smaller than the sum of its proper divisors (34693780).

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

31223540 is a wasteful number, since it uses less digits than its factorization.

31223540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8291 (or 8289 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 31223540 is about 5587.8027882165. The cubic root of 31223540 is about 314.8913373415.

Adding to 31223540 its reverse (4532213), we get a palindrome (35755753).

The spelling of 31223540 in words is "thirty-one million, two hundred twenty-three thousand, five hundred forty".