211970981 has 2 divisors, whose sum is σ = 211970982. Its totient is φ = 211970980.

The previous prime is 211970971. The next prime is 211971017. The reversal of 211970981 is 189079112.

211970981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210105025 + 1865956 = 14495^2 + 1366^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211970981 is a prime.

It is a super-2 number, since 2×211970981² = 89863393572204722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211970911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105985490 + 105985491.

It is an arithmetic number, because the mean of its divisors is an integer number (105985491).

Almost surely, 2^211970981 is an apocalyptic number.

It is an amenable number.

211970981 is a deficient number, since it is larger than the sum of its proper divisors (1).

211970981 is an equidigital number, since it uses as much as digits as its factorization.

211970981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 38.

The square root of 211970981 is about 14559.2232279061. The cubic root of 211970981 is about 596.2459881621.

The spelling of 211970981 in words is "two hundred eleven million, nine hundred seventy thousand, nine hundred eighty-one".