21204103187 has 2 divisors, whose sum is σ = 21204103188. Its totient is φ = 21204103186.

The previous prime is 21204103181. The next prime is 21204103231. The reversal of 21204103187 is 78130140212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21204103187 - 2⁴ = 21204103171 is a prime.

It is a super-2 number, since 2×21204103187² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21204103181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602051593 + 10602051594.

It is an arithmetic number, because the mean of its divisors is an integer number (10602051594).

Almost surely, 2^21204103187 is an apocalyptic number.

21204103187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204103187 is an equidigital number, since it uses as much as digits as its factorization.

21204103187 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

Adding to 21204103187 its reverse (78130140212), we get a palindrome (99334243399).

The spelling of 21204103187 in words is "twenty-one billion, two hundred four million, one hundred three thousand, one hundred eighty-seven".