21311132123 has 4 divisors (see below), whose sum is σ = 21312052560. Its totient is φ = 21310211688.

The previous prime is 21311132077. The next prime is 21311132137. The reversal of 21311132123 is 32123111312.

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 21311132123 - 2³² = 17016164827 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21311132095 and 21311132104.

It is not an unprimeable number, because it can be changed into a prime (21311132173) 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, 424568 + ... + 472101.

It is an arithmetic number, because the mean of its divisors is an integer number (5328013140).

Almost surely, 2^21311132123 is an apocalyptic number.

21311132123 is a deficient number, since it is larger than the sum of its proper divisors (920437).

21311132123 is an equidigital number, since it uses as much as digits as its factorization.

21311132123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 920436.

The product of its digits is 216, while the sum is 20.

Adding to 21311132123 its reverse (32123111312), we get a palindrome (53434243435).

The spelling of 21311132123 in words is "twenty-one billion, three hundred eleven million, one hundred thirty-two thousand, one hundred twenty-three".