21520189 has 2 divisors, whose sum is σ = 21520190. Its totient is φ = 21520188.

The previous prime is 21520159. The next prime is 21520193. The reversal of 21520189 is 98102512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15960025 + 5560164 = 3995^2 + 2358^2 .

It is a cyclic number.

It is not a de Polignac number, because 21520189 - 2⁷ = 21520061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21520139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10760094 + 10760095.

It is an arithmetic number, because the mean of its divisors is an integer number (10760095).

Almost surely, 2^21520189 is an apocalyptic number.

It is an amenable number.

21520189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21520189 is an equidigital number, since it uses as much as digits as its factorization.

21520189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 21520189 is about 4638.9857727740. The cubic root of 21520189 is about 278.1518975628.

The spelling of 21520189 in words is "twenty-one million, five hundred twenty thousand, one hundred eighty-nine".