21223031 has 4 divisors (see below), whose sum is σ = 21273864. Its totient is φ = 21172200.

The previous prime is 21223009. The next prime is 21223051. The reversal of 21223031 is 13032212.

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 21223031 - 2⁶ = 21222967 is a prime.

It is a super-2 number, since 2×21223031² = 900834089653922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21222997 and 21223015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21223051) 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, 24785 + ... + 25626.

It is an arithmetic number, because the mean of its divisors is an integer number (5318466).

Almost surely, 2^21223031 is an apocalyptic number.

21223031 is a deficient number, since it is larger than the sum of its proper divisors (50833).

21223031 is an equidigital number, since it uses as much as digits as its factorization.

21223031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50832.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21223031 is about 4606.8461011846. The cubic root of 21223031 is about 276.8656875119.

Adding to 21223031 its reverse (13032212), we get a palindrome (34255243).

The spelling of 21223031 in words is "twenty-one million, two hundred twenty-three thousand, thirty-one".