21469821 has 4 divisors (see below), whose sum is σ = 28626432. Its totient is φ = 14313212.

The previous prime is 21469807. The next prime is 21469843. The reversal of 21469821 is 12896412.

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 21469821 - 2⁶ = 21469757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21469121) 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, 3578301 + ... + 3578306.

It is an arithmetic number, because the mean of its divisors is an integer number (7156608).

Almost surely, 2^21469821 is an apocalyptic number.

It is an amenable number.

21469821 is a deficient number, since it is larger than the sum of its proper divisors (7156611).

21469821 is an equidigital number, since it uses as much as digits as its factorization.

21469821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7156610.

The product of its digits is 6912, while the sum is 33.

The square root of 21469821 is about 4633.5538196939. The cubic root of 21469821 is about 277.9347232138.

The spelling of 21469821 in words is "twenty-one million, four hundred sixty-nine thousand, eight hundred twenty-one".