21193789 has 2 divisors, whose sum is σ = 21193790. Its totient is φ = 21193788.

The previous prime is 21193769. The next prime is 21193793. The reversal of 21193789 is 98739112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 4588164 = 4075^2 + 2142^2 .

It is a cyclic number.

It is not a de Polignac number, because 21193789 - 2¹³ = 21185597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21193769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10596894 + 10596895.

It is an arithmetic number, because the mean of its divisors is an integer number (10596895).

Almost surely, 2^21193789 is an apocalyptic number.

It is an amenable number.

21193789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21193789 is an equidigital number, since it uses as much as digits as its factorization.

21193789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 40.

The square root of 21193789 is about 4603.6712523811. The cubic root of 21193789 is about 276.7384699361.

The spelling of 21193789 in words is "twenty-one million, one hundred ninety-three thousand, seven hundred eighty-nine".