21125422421 has 8 divisors (see below), whose sum is σ = 22165713024. Its totient is φ = 20095281360.

The previous prime is 21125422391. The next prime is 21125422429. The reversal of 21125422421 is 12422452112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21125422421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125422429) 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 7 ways as a sum of consecutive naturals, for example, 2533121 + ... + 2541446.

It is an arithmetic number, because the mean of its divisors is an integer number (2770714128).

Almost surely, 2^21125422421 is an apocalyptic number.

It is an amenable number.

21125422421 is a deficient number, since it is larger than the sum of its proper divisors (1040290603).

21125422421 is a wasteful number, since it uses less digits than its factorization.

21125422421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5074771.

The product of its digits is 2560, while the sum is 26.

Adding to 21125422421 its reverse (12422452112), we get a palindrome (33547874533).

The spelling of 21125422421 in words is "twenty-one billion, one hundred twenty-five million, four hundred twenty-two thousand, four hundred twenty-one".