21000120999973 has 2 divisors, whose sum is σ = 21000120999974. Its totient is φ = 21000120999972.

The previous prime is 21000120999941. The next prime is 21000121000031. The reversal of 21000120999973 is 37999902100012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19966893475489 + 1033227524484 = 4468433^2 + 1016478^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000120999973 - 2⁵ = 21000120999941 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21000120999973.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000120999373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500060499986 + 10500060499987.

It is an arithmetic number, because the mean of its divisors is an integer number (10500060499987).

Almost surely, 2^{21000120999973} is an apocalyptic number.

It is an amenable number.

21000120999973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000120999973 is an equidigital number, since it uses as much as digits as its factorization.

21000120999973 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 551124, while the sum is 52.

The spelling of 21000120999973 in words is "twenty-one trillion, one hundred twenty million, nine hundred ninety-nine thousand, nine hundred seventy-three".