21235122405 has 144 divisors (see below), whose sum is σ = 45353468160. Its totient is φ = 9499690368.

The previous prime is 21235122397. The next prime is 21235122443. The reversal of 21235122405 is 50422153212.

21235122405 is a `hidden beast` number, since 2 + 1 + 235 + 1 + 22 + 405 = 666.

It is not a de Polignac number, because 21235122405 - 2³ = 21235122397 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 2794351 + ... + 2801939.

It is an arithmetic number, because the mean of its divisors is an integer number (314954640).

Almost surely, 2^21235122405 is an apocalyptic number.

It is an amenable number.

21235122405 is an abundant number, since it is smaller than the sum of its proper divisors (24118345755).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21235122405 is an equidigital number, since it uses as much as digits as its factorization.

21235122405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7670 (or 7651 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

Adding to 21235122405 its reverse (50422153212), we get a palindrome (71657275617).

The spelling of 21235122405 in words is "twenty-one billion, two hundred thirty-five million, one hundred twenty-two thousand, four hundred five".