21138269 has 4 divisors (see below), whose sum is σ = 21484860. Its totient is φ = 20791680.

The previous prime is 21138253. The next prime is 21138277. The reversal of 21138269 is 96283112.

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 4897369 + 16240900 = 2213^2 + 4030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21138269 - 2⁴ = 21138253 is a prime.

It is a super-2 number, since 2×21138269² = 893652832632722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138209) 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, 173204 + ... + 173325.

It is an arithmetic number, because the mean of its divisors is an integer number (5371215).

Almost surely, 2^21138269 is an apocalyptic number.

It is an amenable number.

21138269 is a deficient number, since it is larger than the sum of its proper divisors (346591).

21138269 is an equidigital number, since it uses as much as digits as its factorization.

21138269 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 346590.

The product of its digits is 5184, while the sum is 32.

The square root of 21138269 is about 4597.6373280197. The cubic root of 21138269 is about 276.4966073179.

The spelling of 21138269 in words is "twenty-one million, one hundred thirty-eight thousand, two hundred sixty-nine".