210001201981 has 2 divisors, whose sum is σ = 210001201982. Its totient is φ = 210001201980.

The previous prime is 210001201967. The next prime is 210001201999. The reversal of 210001201981 is 189102100012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 137443698756 + 72557503225 = 370734^2 + 269365^2 .

It is a cyclic number.

It is not a de Polignac number, because 210001201981 - 2⁹ = 210001201469 is a prime.

It is a super-2 number, since 2×210001201981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (210001201681) 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, 105000600990 + 105000600991.

It is an arithmetic number, because the mean of its divisors is an integer number (105000600991).

Almost surely, 2^210001201981 is an apocalyptic number.

It is an amenable number.

210001201981 is a deficient number, since it is larger than the sum of its proper divisors (1).

210001201981 is an equidigital number, since it uses as much as digits as its factorization.

210001201981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 25.

Adding to 210001201981 its reverse (189102100012), we get a palindrome (399103301993).

The spelling of 210001201981 in words is "two hundred ten billion, one million, two hundred one thousand, nine hundred eighty-one".