21101123405 has 16 divisors (see below), whose sum is σ = 26553340080. Its totient is φ = 16075519488.

The previous prime is 21101123387. The next prime is 21101123419. The reversal of 21101123405 is 50432110112.

It can be written as a sum of positive squares in 8 ways, for example, as 1284648964 + 19816474441 = 35842^2 + 140771^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101123405 - 2³² = 16806156109 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 986162 + ... + 1007331.

It is an arithmetic number, because the mean of its divisors is an integer number (1659583755).

Almost surely, 2^21101123405 is an apocalyptic number.

It is an amenable number.

21101123405 is a deficient number, since it is larger than the sum of its proper divisors (5452216675).

21101123405 is a wasteful number, since it uses less digits than its factorization.

21101123405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1993600.

The product of its (nonzero) digits is 240, while the sum is 20.

Adding to 21101123405 its reverse (50432110112), we get a palindrome (71533233517).

The spelling of 21101123405 in words is "twenty-one billion, one hundred one million, one hundred twenty-three thousand, four hundred five".