21131133123 has 4 divisors (see below), whose sum is σ = 28174844168. Its totient is φ = 14087422080.

The previous prime is 21131133073. The next prime is 21131133173. The reversal of 21131133123 is 32133113112.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (21131133073) and next prime (21131133173).

It is not a de Polignac number, because 21131133123 - 2⁹ = 21131132611 is a prime.

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 21131133123.

It is not an unprimeable number, because it can be changed into a prime (21131133173) 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, 3521855518 + ... + 3521855523.

It is an arithmetic number, because the mean of its divisors is an integer number (7043711042).

Almost surely, 2^21131133123 is an apocalyptic number.

21131133123 is a deficient number, since it is larger than the sum of its proper divisors (7043711045).

21131133123 is an equidigital number, since it uses as much as digits as its factorization.

21131133123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7043711044.

The product of its digits is 324, while the sum is 21.

Adding to 21131133123 its reverse (32133113112), we get a palindrome (53264246235).

The spelling of 21131133123 in words is "twenty-one billion, one hundred thirty-one million, one hundred thirty-three thousand, one hundred twenty-three".