21012001221187 has 2 divisors, whose sum is σ = 21012001221188. Its totient is φ = 21012001221186.

The previous prime is 21012001221121. The next prime is 21012001221287. The reversal of 21012001221187 is 78112210021012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012001221187 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012001221287) 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, 10506000610593 + 10506000610594.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000610594).

Almost surely, 2^{21012001221187} is an apocalyptic number.

21012001221187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001221187 is an equidigital number, since it uses as much as digits as its factorization.

21012001221187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 28.

Adding to 21012001221187 its reverse (78112210021012), we get a palindrome (99124211242199).

The spelling of 21012001221187 in words is "twenty-one trillion, twelve billion, one million, two hundred twenty-one thousand, one hundred eighty-seven".