21311033123 has 4 divisors (see below), whose sum is σ = 21312771480. Its totient is φ = 21309294768.

The previous prime is 21311033113. The next prime is 21311033141. The reversal of 21311033123 is 32133011312.

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 21311033123 - 2⁶ = 21311033059 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21311033095 and 21311033104.

It is not an unprimeable number, because it can be changed into a prime (21311033113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 850658 + ... + 875351.

It is an arithmetic number, because the mean of its divisors is an integer number (5328192870).

Almost surely, 2^21311033123 is an apocalyptic number.

21311033123 is a deficient number, since it is larger than the sum of its proper divisors (1738357).

21311033123 is a wasteful number, since it uses less digits than its factorization.

21311033123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1738356.

The product of its (nonzero) digits is 324, while the sum is 20.

Adding to 21311033123 its reverse (32133011312), we get a palindrome (53444044435).

The spelling of 21311033123 in words is "twenty-one billion, three hundred eleven million, thirty-three thousand, one hundred twenty-three".