21033989 has 2 divisors, whose sum is σ = 21033990. Its totient is φ = 21033988.

The previous prime is 21033979. The next prime is 21034003. The reversal of 21033989 is 98933012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20340100 + 693889 = 4510^2 + 833^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033989 - 2⁴ = 21033973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21033919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516994 + 10516995.

It is an arithmetic number, because the mean of its divisors is an integer number (10516995).

Almost surely, 2^21033989 is an apocalyptic number.

It is an amenable number.

21033989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033989 is an equidigital number, since it uses as much as digits as its factorization.

21033989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 21033989 is about 4586.2826995291. The cubic root of 21033989 is about 276.0411835555.

It can be divided in two parts, 21033 and 989, that added together give a palindrome (22022).

The spelling of 21033989 in words is "twenty-one million, thirty-three thousand, nine hundred eighty-nine".