21331789 has 2 divisors, whose sum is σ = 21331790. Its totient is φ = 21331788.

The previous prime is 21331781. The next prime is 21331819. The reversal of 21331789 is 98713312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14122564 + 7209225 = 3758^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 21331789 - 2³ = 21331781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21331781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665894 + 10665895.

It is an arithmetic number, because the mean of its divisors is an integer number (10665895).

Almost surely, 2^21331789 is an apocalyptic number.

It is an amenable number.

21331789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331789 is an equidigital number, since it uses as much as digits as its factorization.

21331789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 34.

The square root of 21331789 is about 4618.6349715040. The cubic root of 21331789 is about 277.3378171980.

The spelling of 21331789 in words is "twenty-one million, three hundred thirty-one thousand, seven hundred eighty-nine".