21913189 has 2 divisors, whose sum is σ = 21913190. Its totient is φ = 21913188.

The previous prime is 21913169. The next prime is 21913201. The reversal of 21913189 is 98131912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21696964 + 216225 = 4658^2 + 465^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21913189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21913109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10956594 + 10956595.

It is an arithmetic number, because the mean of its divisors is an integer number (10956595).

Almost surely, 2^21913189 is an apocalyptic number.

It is an amenable number.

21913189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21913189 is an equidigital number, since it uses as much as digits as its factorization.

21913189 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 34.

The square root of 21913189 is about 4681.1525290253. The cubic root of 21913189 is about 279.8348899021.

It can be divided in two parts, 2 and 1913189, that added together give a palindrome (1913191).

The spelling of 21913189 in words is "twenty-one million, nine hundred thirteen thousand, one hundred eighty-nine".