21421121201 has 4 divisors (see below), whose sum is σ = 22681187172. Its totient is φ = 20161055232.

The previous prime is 21421121171. The next prime is 21421121203. The reversal of 21421121201 is 10212112412.

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 16063027600 + 5358093601 = 126740^2 + 73199^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421121201 - 2¹⁰ = 21421120177 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1260065953 = 21421121201 / (2 + 1 + 4 + 2 + 1 + 1 + 2 + 1 + 2 + 0 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21421121201.

It is not an unprimeable number, because it can be changed into a prime (21421121203) 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, 630032960 + ... + 630032993.

It is an arithmetic number, because the mean of its divisors is an integer number (5670296793).

Almost surely, 2^21421121201 is an apocalyptic number.

It is an amenable number.

21421121201 is a deficient number, since it is larger than the sum of its proper divisors (1260065971).

21421121201 is a wasteful number, since it uses less digits than its factorization.

21421121201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1260065970.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21421121201 its reverse (10212112412), we get a palindrome (31633233613).

The spelling of 21421121201 in words is "twenty-one billion, four hundred twenty-one million, one hundred twenty-one thousand, two hundred one".