222121721 has 2 divisors, whose sum is σ = 222121722. Its totient is φ = 222121720.

The previous prime is 222121717. The next prime is 222121729. The reversal of 222121721 is 127121222.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 206209600 + 15912121 = 14360^2 + 3989^2 .

It is a cyclic number.

It is not a de Polignac number, because 222121721 - 2² = 222121717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 222121693 and 222121702.

It is not a weakly prime, because it can be changed into another prime (222121729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 111060860 + 111060861.

It is an arithmetic number, because the mean of its divisors is an integer number (111060861).

Almost surely, 2^222121721 is an apocalyptic number.

It is an amenable number.

222121721 is a deficient number, since it is larger than the sum of its proper divisors (1).

222121721 is an equidigital number, since it uses as much as digits as its factorization.

222121721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 224, while the sum is 20.

The square root of 222121721 is about 14903.7485553132. The cubic root of 222121721 is about 605.6155390883.

Adding to 222121721 its reverse (127121222), we get a palindrome (349242943).

The spelling of 222121721 in words is "two hundred twenty-two million, one hundred twenty-one thousand, seven hundred twenty-one".