21210197912851 has 2 divisors, whose sum is σ = 21210197912852. Its totient is φ = 21210197912850.

The previous prime is 21210197912831. The next prime is 21210197912857. The reversal of 21210197912851 is 15821979101212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21210197912851 - 2⁵ = 21210197912819 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21210197912795 and 21210197912804.

It is not a weakly prime, because it can be changed into another prime (21210197912857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605098956425 + 10605098956426.

It is an arithmetic number, because the mean of its divisors is an integer number (10605098956426).

Almost surely, 2^{21210197912851} is an apocalyptic number.

21210197912851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210197912851 is an equidigital number, since it uses as much as digits as its factorization.

21210197912851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 49.

The spelling of 21210197912851 in words is "twenty-one trillion, two hundred ten billion, one hundred ninety-seven million, nine hundred twelve thousand, eight hundred fifty-one".