21041989 has 2 divisors, whose sum is σ = 21041990. Its totient is φ = 21041988.

The previous prime is 21041983. The next prime is 21042013. The reversal of 21041989 is 98914012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10692900 + 10349089 = 3270^2 + 3217^2 .

It is a cyclic number.

It is not a de Polignac number, because 21041989 - 2³ = 21041981 is a prime.

It is a super-2 number, since 2×21041989² = 885530602152242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21041981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520994 + 10520995.

It is an arithmetic number, because the mean of its divisors is an integer number (10520995).

Almost surely, 2^21041989 is an apocalyptic number.

It is an amenable number.

21041989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21041989 is an equidigital number, since it uses as much as digits as its factorization.

21041989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21041989 is about 4587.1547826512. The cubic root of 21041989 is about 276.0761753262.

The spelling of 21041989 in words is "twenty-one million, forty-one thousand, nine hundred eighty-nine".