21223679 has 4 divisors (see below), whose sum is σ = 21955560. Its totient is φ = 20491800.

The previous prime is 21223673. The next prime is 21223693. The reversal of 21223679 is 97632212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21223679 - 2⁴ = 21223663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21223673) 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, 365897 + ... + 365954.

It is an arithmetic number, because the mean of its divisors is an integer number (5488890).

Almost surely, 2^21223679 is an apocalyptic number.

21223679 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21223679 is a deficient number, since it is larger than the sum of its proper divisors (731881).

21223679 is an equidigital number, since it uses as much as digits as its factorization.

21223679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731880.

The product of its digits is 9072, while the sum is 32.

The square root of 21223679 is about 4606.9164307593. The cubic root of 21223679 is about 276.8685053177.

The spelling of 21223679 in words is "twenty-one million, two hundred twenty-three thousand, six hundred seventy-nine".