210397981 has 2 divisors, whose sum is σ = 210397982. Its totient is φ = 210397980.

The previous prime is 210397949. The next prime is 210398009. The reversal of 210397981 is 189793012.

210397981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209525625 + 872356 = 14475^2 + 934^2 .

It is a cyclic number.

It is not a de Polignac number, because 210397981 - 2⁵ = 210397949 is a prime.

It is a super-2 number, since 2×210397981² = 88534620817752722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (210397931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105198990 + 105198991.

It is an arithmetic number, because the mean of its divisors is an integer number (105198991).

Almost surely, 2^210397981 is an apocalyptic number.

It is an amenable number.

210397981 is a deficient number, since it is larger than the sum of its proper divisors (1).

210397981 is an equidigital number, since it uses as much as digits as its factorization.

210397981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 210397981 is about 14505.1018955401. The cubic root of 210397981 is about 594.7674453092.

The spelling of 210397981 in words is "two hundred ten million, three hundred ninety-seven thousand, nine hundred eighty-one".