31870221 has 4 divisors (see below), whose sum is σ = 42493632. Its totient is φ = 21246812.

The previous prime is 31870219. The next prime is 31870231. The reversal of 31870221 is 12207813.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12207813 = 3 ⋅4069271.

It is a cyclic number.

It is not a de Polignac number, because 31870221 - 2¹ = 31870219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31870191 and 31870200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31870231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5311701 + ... + 5311706.

It is an arithmetic number, because the mean of its divisors is an integer number (10623408).

Almost surely, 2^31870221 is an apocalyptic number.

It is an amenable number.

31870221 is a deficient number, since it is larger than the sum of its proper divisors (10623411).

31870221 is a wasteful number, since it uses less digits than its factorization.

31870221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10623410.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 31870221 is about 5645.3716440993. The cubic root of 31870221 is about 317.0504386234.

The spelling of 31870221 in words is "thirty-one million, eight hundred seventy thousand, two hundred twenty-one".