21221023 has 4 divisors (see below), whose sum is σ = 21232728. Its totient is φ = 21209320.

The previous prime is 21221021. The next prime is 21221033. The reversal of 21221023 is 32012212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21221023 - 2¹ = 21221021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21220994 and 21221012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221021) 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, 2488 + ... + 6973.

It is an arithmetic number, because the mean of its divisors is an integer number (5308182).

Almost surely, 2^21221023 is an apocalyptic number.

21221023 is a deficient number, since it is larger than the sum of its proper divisors (11705).

21221023 is an equidigital number, since it uses as much as digits as its factorization.

21221023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11704.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21221023 is about 4606.6281595110. The cubic root of 21221023 is about 276.8569554285.

Adding to 21221023 its reverse (32012212), we get a palindrome (53233235).

It can be divided in two parts, 2 and 1221023, that added together give a square (1221025 = 1105²).

The spelling of 21221023 in words is "twenty-one million, two hundred twenty-one thousand, twenty-three".