31221032221 has 4 divisors (see below), whose sum is σ = 31430569500. Its totient is φ = 31011494944.

The previous prime is 31221032203. The next prime is 31221032233. The reversal of 31221032221 is 12223012213.

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 1270922500 + 29950109721 = 35650^2 + 173061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31221032221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31221032021) 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, 104768416 + ... + 104768713.

It is an arithmetic number, because the mean of its divisors is an integer number (7857642375).

Almost surely, 2^31221032221 is an apocalyptic number.

It is an amenable number.

31221032221 is a deficient number, since it is larger than the sum of its proper divisors (209537279).

31221032221 is a wasteful number, since it uses less digits than its factorization.

31221032221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209537278.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 31221032221 its reverse (12223012213), we get a palindrome (43444044434).

The spelling of 31221032221 in words is "thirty-one billion, two hundred twenty-one million, thirty-two thousand, two hundred twenty-one".