21254430121 has 4 divisors (see below), whose sum is σ = 21545586772. Its totient is φ = 20963273472.

The previous prime is 21254430103. The next prime is 21254430137. The reversal of 21254430121 is 12103445212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5694362521 + 15560067600 = 75461^2 + 124740^2 .

It is a cyclic number.

It is not a de Polignac number, because 21254430121 - 2¹⁷ = 21254299049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21254430221) 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, 145578216 + ... + 145578361.

It is an arithmetic number, because the mean of its divisors is an integer number (5386396693).

Almost surely, 2^21254430121 is an apocalyptic number.

It is an amenable number.

21254430121 is a deficient number, since it is larger than the sum of its proper divisors (291156651).

21254430121 is an equidigital number, since it uses as much as digits as its factorization.

21254430121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291156650.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 21254430121 its reverse (12103445212), we get a palindrome (33357875333).

The spelling of 21254430121 in words is "twenty-one billion, two hundred fifty-four million, four hundred thirty thousand, one hundred twenty-one".