21017189 has 2 divisors, whose sum is σ = 21017190. Its totient is φ = 21017188.

The previous prime is 21017179. The next prime is 21017197. The reversal of 21017189 is 98171012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15864289 + 5152900 = 3983^2 + 2270^2 .

It is a cyclic number.

It is not a de Polignac number, because 21017189 - 2¹² = 21013093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21017149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10508594 + 10508595.

It is an arithmetic number, because the mean of its divisors is an integer number (10508595).

Almost surely, 2^21017189 is an apocalyptic number.

It is an amenable number.

21017189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21017189 is an equidigital number, since it uses as much as digits as its factorization.

21017189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 21017189 is about 4584.4507849905. The cubic root of 21017189 is about 275.9676719469.

The spelling of 21017189 in words is "twenty-one million, seventeen thousand, one hundred eighty-nine".