21231051123 has 4 divisors (see below), whose sum is σ = 28308068168. Its totient is φ = 14154034080.

The previous prime is 21231051113. The next prime is 21231051131. The reversal of 21231051123 is 32115013212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21231051123 - 2²⁹ = 20694180211 is a prime.

It is a super-2 number, since 2×21231051123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21231051123.

It is not an unprimeable number, because it can be changed into a prime (21231051113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3538508518 + ... + 3538508523.

It is an arithmetic number, because the mean of its divisors is an integer number (7077017042).

Almost surely, 2^21231051123 is an apocalyptic number.

21231051123 is a deficient number, since it is larger than the sum of its proper divisors (7077017045).

21231051123 is an equidigital number, since it uses as much as digits as its factorization.

21231051123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7077017044.

The product of its (nonzero) digits is 360, while the sum is 21.

Adding to 21231051123 its reverse (32115013212), we get a palindrome (53346064335).

The spelling of 21231051123 in words is "twenty-one billion, two hundred thirty-one million, fifty-one thousand, one hundred twenty-three".