21423569 has 4 divisors (see below), whose sum is σ = 21444096. Its totient is φ = 21403044.

The previous prime is 21423559. The next prime is 21423581. The reversal of 21423569 is 96532412.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-21423569 is a prime.

It is a super-2 number, since 2×21423569² = 917938617395522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21423509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8609 + ... + 10814.

It is an arithmetic number, because the mean of its divisors is an integer number (5361024).

Almost surely, 2^21423569 is an apocalyptic number.

It is an amenable number.

21423569 is a deficient number, since it is larger than the sum of its proper divisors (20527).

21423569 is a wasteful number, since it uses less digits than its factorization.

21423569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20526.

The product of its digits is 12960, while the sum is 32.

The square root of 21423569 is about 4628.5601432843. The cubic root of 21423569 is about 277.7349966767.

The spelling of 21423569 in words is "twenty-one million, four hundred twenty-three thousand, five hundred sixty-nine".