3121100221 has 2 divisors, whose sum is σ = 3121100222. Its totient is φ = 3121100220.

The previous prime is 3121100219. The next prime is 3121100231. The reversal of 3121100221 is 1220011213.

3121100221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1600880121 + 1520220100 = 40011^2 + 38990^2 .

It is a cyclic number.

It is not a de Polignac number, because 3121100221 - 2¹ = 3121100219 is a prime.

Together with 3121100219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3121100201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1560550110 + 1560550111.

It is an arithmetic number, because the mean of its divisors is an integer number (1560550111).

Almost surely, 2^3121100221 is an apocalyptic number.

It is an amenable number.

3121100221 is a deficient number, since it is larger than the sum of its proper divisors (1).

3121100221 is an equidigital number, since it uses as much as digits as its factorization.

3121100221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 3121100221 is about 55866.8078647778. The cubic root of 3121100221 is about 1461.4004547250.

Adding to 3121100221 its reverse (1220011213), we get a palindrome (4341111434).

The spelling of 3121100221 in words is "three billion, one hundred twenty-one million, one hundred thousand, two hundred twenty-one".