21101281123 has 4 divisors (see below), whose sum is σ = 22724456608. Its totient is φ = 19478105640.

The previous prime is 21101281073. The next prime is 21101281129. The reversal of 21101281123 is 32118210112.

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 21101281123 - 2⁹ = 21101280611 is a prime.

It is a super-2 number, since 2×21101281123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101281094 and 21101281103.

It is not an unprimeable number, because it can be changed into a prime (21101281129) 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, 811587723 + ... + 811587748.

It is an arithmetic number, because the mean of its divisors is an integer number (5681114152).

Almost surely, 2^21101281123 is an apocalyptic number.

21101281123 is a deficient number, since it is larger than the sum of its proper divisors (1623175485).

21101281123 is a wasteful number, since it uses less digits than its factorization.

21101281123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1623175484.

The product of its (nonzero) digits is 192, while the sum is 22.

Adding to 21101281123 its reverse (32118210112), we get a palindrome (53219491235).

The spelling of 21101281123 in words is "twenty-one billion, one hundred one million, two hundred eighty-one thousand, one hundred twenty-three".