21712223 has 4 divisors (see below), whose sum is σ = 23382408. Its totient is φ = 20042040.

The previous prime is 21712211. The next prime is 21712237. The reversal of 21712223 is 32221712.

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 21712223 - 2⁸ = 21711967 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21712195 and 21712204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21712283) 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, 835073 + ... + 835098.

It is an arithmetic number, because the mean of its divisors is an integer number (5845602).

Almost surely, 2^21712223 is an apocalyptic number.

21712223 is a deficient number, since it is larger than the sum of its proper divisors (1670185).

21712223 is a wasteful number, since it uses less digits than its factorization.

21712223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1670184.

The product of its digits is 336, while the sum is 20.

The square root of 21712223 is about 4659.6376468562. The cubic root of 21712223 is about 278.9768054955.

Adding to 21712223 its reverse (32221712), we get a palindrome (53933935).

The spelling of 21712223 in words is "twenty-one million, seven hundred twelve thousand, two hundred twenty-three".