21002104251 has 32 divisors (see below), whose sum is σ = 31790346240. Its totient is φ = 13699562400.

The previous prime is 21002104237. The next prime is 21002104261. The reversal of 21002104251 is 15240120012.

It is not a de Polignac number, because 21002104251 - 2⁵ = 21002104219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21002104231) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 281196 + ... + 347958.

It is an arithmetic number, because the mean of its divisors is an integer number (993448320).

Almost surely, 2^21002104251 is an apocalyptic number.

21002104251 is a deficient number, since it is larger than the sum of its proper divisors (10788241989).

21002104251 is a wasteful number, since it uses less digits than its factorization.

21002104251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67024 (or 67018 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

Adding to 21002104251 its reverse (15240120012), we get a palindrome (36242224263).

The spelling of 21002104251 in words is "twenty-one billion, two million, one hundred four thousand, two hundred fifty-one".