21135040421 has 4 divisors (see below), whose sum is σ = 23056407744. Its totient is φ = 19213673100.

The previous prime is 21135040369. The next prime is 21135040439. The reversal of 21135040421 is 12404053112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21135040421 - 2³⁰ = 20061298597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135040721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 960683645 + ... + 960683666.

It is an arithmetic number, because the mean of its divisors is an integer number (5764101936).

Almost surely, 2^21135040421 is an apocalyptic number.

It is an amenable number.

21135040421 is a deficient number, since it is larger than the sum of its proper divisors (1921367323).

21135040421 is a wasteful number, since it uses less digits than its factorization.

21135040421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1921367322.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21135040421 its reverse (12404053112), we get a palindrome (33539093533).

The spelling of 21135040421 in words is "twenty-one billion, one hundred thirty-five million, forty thousand, four hundred twenty-one".