21209269 has 4 divisors (see below), whose sum is σ = 21227500. Its totient is φ = 21191040.

The previous prime is 21209231. The next prime is 21209311. The reversal of 21209269 is 96290212.

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 16200625 + 5008644 = 4025^2 + 2238^2 .

It is a cyclic number.

It is not a de Polignac number, because 21209269 - 2⁷ = 21209141 is a prime.

It is a super-2 number, since 2×21209269² = 899666183028722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21209269.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21209369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7242 + ... + 9739.

It is an arithmetic number, because the mean of its divisors is an integer number (5306875).

Almost surely, 2^21209269 is an apocalyptic number.

It is an amenable number.

21209269 is a deficient number, since it is larger than the sum of its proper divisors (18231).

21209269 is a wasteful number, since it uses less digits than its factorization.

21209269 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18230.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 21209269 is about 4605.3522123720. The cubic root of 21209269 is about 276.8058303774.

The spelling of 21209269 in words is "twenty-one million, two hundred nine thousand, two hundred sixty-nine".