21231123 has 4 divisors (see below), whose sum is σ = 28308168. Its totient is φ = 14154080.

The previous prime is 21231107. The next prime is 21231143. The reversal of 21231123 is 32113212.

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 21231123 - 2⁴ = 21231107 is a prime.

It is a super-2 number, since 2×21231123² = 901521167682258, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21231143) 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, 3538518 + ... + 3538523.

It is an arithmetic number, because the mean of its divisors is an integer number (7077042).

Almost surely, 2^21231123 is an apocalyptic number.

21231123 is a deficient number, since it is larger than the sum of its proper divisors (7077045).

21231123 is an equidigital number, since it uses as much as digits as its factorization.

21231123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7077044.

The product of its digits is 72, while the sum is 15.

The square root of 21231123 is about 4607.7242756050. The cubic root of 21231123 is about 276.9008711836.

Adding to 21231123 its reverse (32113212), we get a palindrome (53344335).

The spelling of 21231123 in words is "twenty-one million, two hundred thirty-one thousand, one hundred twenty-three".