21663269 has 4 divisors (see below), whose sum is σ = 21873696. Its totient is φ = 21452844.

The previous prime is 21663251. The next prime is 21663277. The reversal of 21663269 is 96236612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21663269 - 2¹⁶ = 21597733 is a prime.

It is a super-2 number, since 2×21663269² = 938594447532722, 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 (21663209) 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, 105059 + ... + 105264.

It is an arithmetic number, because the mean of its divisors is an integer number (5468424).

Almost surely, 2^21663269 is an apocalyptic number.

It is an amenable number.

21663269 is a deficient number, since it is larger than the sum of its proper divisors (210427).

21663269 is a wasteful number, since it uses less digits than its factorization.

21663269 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210426.

The product of its digits is 23328, while the sum is 35.

The square root of 21663269 is about 4654.3816990015. The cubic root of 21663269 is about 278.7669804050.

The spelling of 21663269 in words is "twenty-one million, six hundred sixty-three thousand, two hundred sixty-nine".