21401044121 has 4 divisors (see below), whose sum is σ = 21405811812. Its totient is φ = 21396276432.

The previous prime is 21401044043. The next prime is 21401044139. The reversal of 21401044121 is 12144010412.

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 14270930521 + 7130113600 = 119461^2 + 84440^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21401044121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21401044093 and 21401044102.

It is not an unprimeable number, because it can be changed into a prime (21401044141) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 2377106 + ... + 2386091.

It is an arithmetic number, because the mean of its divisors is an integer number (5351452953).

Almost surely, 2^21401044121 is an apocalyptic number.

It is an amenable number.

21401044121 is a deficient number, since it is larger than the sum of its proper divisors (4767691).

21401044121 is an equidigital number, since it uses as much as digits as its factorization.

21401044121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4767690.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21401044121 its reverse (12144010412), we get a palindrome (33545054533).

The spelling of 21401044121 in words is "twenty-one billion, four hundred one million, forty-four thousand, one hundred twenty-one".