23721221 has 2 divisors, whose sum is σ = 23721222. Its totient is φ = 23721220.

The previous prime is 23721199. The next prime is 23721223. The reversal of 23721221 is 12212732.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13060996 + 10660225 = 3614^2 + 3265^2 .

It is a cyclic number.

It is not a de Polignac number, because 23721221 - 2¹⁰ = 23720197 is a prime.

Together with 23721223, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 23721193 and 23721202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23721223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11860610 + 11860611.

It is an arithmetic number, because the mean of its divisors is an integer number (11860611).

Almost surely, 2^23721221 is an apocalyptic number.

It is an amenable number.

23721221 is a deficient number, since it is larger than the sum of its proper divisors (1).

23721221 is an equidigital number, since it uses as much as digits as its factorization.

23721221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 336, while the sum is 20.

The square root of 23721221 is about 4870.4436142922. The cubic root of 23721221 is about 287.3287035045.

Adding to 23721221 its reverse (12212732), we get a palindrome (35933953).

The spelling of 23721221 in words is "twenty-three million, seven hundred twenty-one thousand, two hundred twenty-one".