21254789 has 2 divisors, whose sum is σ = 21254790. Its totient is φ = 21254788.

The previous prime is 21254729. The next prime is 21254797. The reversal of 21254789 is 98745212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18748900 + 2505889 = 4330^2 + 1583^2 .

It is a cyclic number.

It is not a de Polignac number, because 21254789 - 2¹² = 21250693 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21254729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627394 + 10627395.

It is an arithmetic number, because the mean of its divisors is an integer number (10627395).

Almost surely, 2^21254789 is an apocalyptic number.

It is an amenable number.

21254789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21254789 is an equidigital number, since it uses as much as digits as its factorization.

21254789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 38.

The square root of 21254789 is about 4610.2916393651. The cubic root of 21254789 is about 277.0037186657.

The spelling of 21254789 in words is "twenty-one million, two hundred fifty-four thousand, seven hundred eighty-nine".