223656721 has 2 divisors, whose sum is σ = 223656722. Its totient is φ = 223656720.

The previous prime is 223656679. The next prime is 223656737. The reversal of 223656721 is 127656322.

223656721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138297600 + 85359121 = 11760^2 + 9239^2 .

It is a cyclic number.

It is not a de Polignac number, because 223656721 - 2¹⁹ = 223132433 is a prime.

It is not a weakly prime, because it can be changed into another prime (223659721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 111828360 + 111828361.

It is an arithmetic number, because the mean of its divisors is an integer number (111828361).

Almost surely, 2^223656721 is an apocalyptic number.

It is an amenable number.

223656721 is a deficient number, since it is larger than the sum of its proper divisors (1).

223656721 is an equidigital number, since it uses as much as digits as its factorization.

223656721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 34.

The square root of 223656721 is about 14955.1570035222. The cubic root of 223656721 is about 607.0073984914.

The spelling of 223656721 in words is "two hundred twenty-three million, six hundred fifty-six thousand, seven hundred twenty-one".