21222431 has 4 divisors (see below), whose sum is σ = 21339864. Its totient is φ = 21105000.

The previous prime is 21222401. The next prime is 21222433. The reversal of 21222431 is 13422212.

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 21222431 - 2⁶ = 21222367 is a prime.

It is a super-2 number, since 2×21222431² = 900783155099522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58445 + ... + 58806.

It is an arithmetic number, because the mean of its divisors is an integer number (5334966).

Almost surely, 2^21222431 is an apocalyptic number.

21222431 is a deficient number, since it is larger than the sum of its proper divisors (117433).

21222431 is a wasteful number, since it uses less digits than its factorization.

21222431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117432.

The product of its digits is 192, while the sum is 17.

The square root of 21222431 is about 4606.7809802507. The cubic root of 21222431 is about 276.8630783814.

Adding to 21222431 its reverse (13422212), we get a palindrome (34644643).

The spelling of 21222431 in words is "twenty-one million, two hundred twenty-two thousand, four hundred thirty-one".