721112221 has 2 divisors, whose sum is σ = 721112222. Its totient is φ = 721112220.

The previous prime is 721112213. The next prime is 721112243. The reversal of 721112221 is 122211127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 689640121 + 31472100 = 26261^2 + 5610^2 .

It is a cyclic number.

It is not a de Polignac number, because 721112221 - 2³ = 721112213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721512221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360556110 + 360556111.

It is an arithmetic number, because the mean of its divisors is an integer number (360556111).

Almost surely, 2^721112221 is an apocalyptic number.

It is an amenable number.

721112221 is a deficient number, since it is larger than the sum of its proper divisors (1).

721112221 is an equidigital number, since it uses as much as digits as its factorization.

721112221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 112, while the sum is 19.

The square root of 721112221 is about 26853.5327471080. The cubic root of 721112221 is about 896.7422222893.

Adding to 721112221 its reverse (122211127), we get a palindrome (843323348).

The spelling of 721112221 in words is "seven hundred twenty-one million, one hundred twelve thousand, two hundred twenty-one".