31201212221 has 4 divisors (see below), whose sum is σ = 31228849500. Its totient is φ = 31173574944.

The previous prime is 31201212181. The next prime is 31201212233. The reversal of 31201212221 is 12221210213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12221210213 = 43 ⋅284214191.

It can be written as a sum of positive squares in 2 ways, for example, as 20089944121 + 11111268100 = 141739^2 + 105410^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31201212221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31201212221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31201212271) 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, 13816946 + ... + 13819203.

It is an arithmetic number, because the mean of its divisors is an integer number (7807212375).

Almost surely, 2^31201212221 is an apocalyptic number.

It is an amenable number.

31201212221 is a deficient number, since it is larger than the sum of its proper divisors (27637279).

31201212221 is a wasteful number, since it uses less digits than its factorization.

31201212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27637278.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 31201212221 its reverse (12221210213), we get a palindrome (43422422434).

The spelling of 31201212221 in words is "thirty-one billion, two hundred one million, two hundred twelve thousand, two hundred twenty-one".