21252389 has 4 divisors (see below), whose sum is σ = 21985260. Its totient is φ = 20519520.

The previous prime is 21252383. The next prime is 21252401. The reversal of 21252389 is 98325212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11222500 + 10029889 = 3350^2 + 3167^2 .

It is a cyclic number.

It is not a de Polignac number, because 21252389 - 2⁴ = 21252373 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252383) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 366392 + ... + 366449.

It is an arithmetic number, because the mean of its divisors is an integer number (5496315).

Almost surely, 2^21252389 is an apocalyptic number.

21252389 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21252389 is a deficient number, since it is larger than the sum of its proper divisors (732871).

21252389 is an equidigital number, since it uses as much as digits as its factorization.

21252389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 732870.

The product of its digits is 8640, while the sum is 32.

The square root of 21252389 is about 4610.0313447958. The cubic root of 21252389 is about 276.9932922477.

The spelling of 21252389 in words is "twenty-one million, two hundred fifty-two thousand, three hundred eighty-nine".