31725221 has 8 divisors (see below), whose sum is σ = 34860000. Its totient is φ = 28632240.

The previous prime is 31725209. The next prime is 31725241. The reversal of 31725221 is 12252713.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31725221 - 2¹⁸ = 31463077 is a prime.

It is a super-3 number, since 3×31725221³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31725241) 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, 8846 + ... + 11903.

It is an arithmetic number, because the mean of its divisors is an integer number (4357500).

Almost surely, 2^31725221 is an apocalyptic number.

It is an amenable number.

31725221 is a deficient number, since it is larger than the sum of its proper divisors (3134779).

31725221 is a wasteful number, since it uses less digits than its factorization.

31725221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20899.

The product of its digits is 840, while the sum is 23.

The square root of 31725221 is about 5632.5146249255. The cubic root of 31725221 is about 316.5688792552.

Adding to 31725221 its reverse (12252713), we get a palindrome (43977934).

The spelling of 31725221 in words is "thirty-one million, seven hundred twenty-five thousand, two hundred twenty-one".