31421221 has 4 divisors (see below), whose sum is σ = 33838252. Its totient is φ = 29004192.

The previous prime is 31421213. The next prime is 31421233. The reversal of 31421221 is 12212413.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1718721 + 29702500 = 1311^2 + 5450^2 .

It is a cyclic number.

It is not a de Polignac number, because 31421221 - 2³ = 31421213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31421195 and 31421204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31424221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1208496 + ... + 1208521.

It is an arithmetic number, because the mean of its divisors is an integer number (8459563).

Almost surely, 2^31421221 is an apocalyptic number.

It is an amenable number.

31421221 is a deficient number, since it is larger than the sum of its proper divisors (2417031).

31421221 is a wasteful number, since it uses less digits than its factorization.

31421221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2417030.

The product of its digits is 96, while the sum is 16.

The square root of 31421221 is about 5605.4634955550. The cubic root of 31421221 is about 315.5544815302.

Adding to 31421221 its reverse (12212413), we get a palindrome (43633634).

The spelling of 31421221 in words is "thirty-one million, four hundred twenty-one thousand, two hundred twenty-one".