31225216 has 64 divisors (see below), whose sum is σ = 69082560. Its totient is φ = 13939200.

The previous prime is 31225213. The next prime is 31225247. The reversal of 31225216 is 61252213.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×31225216² = 1950028228493312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31225213) 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, 94171 + ... + 94501.

It is an arithmetic number, because the mean of its divisors is an integer number (1079415).

Almost surely, 2^31225216 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 31225216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34541280).

31225216 is an abundant number, since it is smaller than the sum of its proper divisors (37857344).

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

31225216 is a wasteful number, since it uses less digits than its factorization.

31225216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423 (or 411 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 31225216 is about 5587.9527557058. The cubic root of 31225216 is about 314.8969714287.

Adding to 31225216 its reverse (61252213), we get a palindrome (92477429).

It can be divided in two parts, 3122 and 5216, that added together give a palindrome (8338).

The spelling of 31225216 in words is "thirty-one million, two hundred twenty-five thousand, two hundred sixteen".