21223811 has 16 divisors (see below), whose sum is σ = 25344000. Its totient is φ = 17756424.

The previous prime is 21223793. The next prime is 21223823. The reversal of 21223811 is 11832212.

It is not a de Polignac number, because 21223811 - 2¹⁰ = 21222787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21223841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14030 + ... + 15468.

It is an arithmetic number, because the mean of its divisors is an integer number (1584000).

Almost surely, 2^21223811 is an apocalyptic number.

21223811 is a deficient number, since it is larger than the sum of its proper divisors (4120189).

21223811 is an equidigital number, since it uses as much as digits as its factorization.

21223811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503 (or 1489 counting only the distinct ones).

The product of its digits is 192, while the sum is 20.

The square root of 21223811 is about 4606.9307570225. The cubic root of 21223811 is about 276.8690793082.

The spelling of 21223811 in words is "twenty-one million, two hundred twenty-three thousand, eight hundred eleven".