212099981 has 2 divisors, whose sum is σ = 212099982. Its totient is φ = 212099980.

The previous prime is 212099941. The next prime is 212100017. The reversal of 212099981 is 189990212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 110775625 + 101324356 = 10525^2 + 10066^2 .

It is a cyclic number.

It is not a de Polignac number, because 212099981 - 2⁶ = 212099917 is a prime.

It is a super-2 number, since 2×212099981² = 89972803880400722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212099941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106049990 + 106049991.

It is an arithmetic number, because the mean of its divisors is an integer number (106049991).

Almost surely, 2^212099981 is an apocalyptic number.

It is an amenable number.

212099981 is a deficient number, since it is larger than the sum of its proper divisors (1).

212099981 is an equidigital number, since it uses as much as digits as its factorization.

212099981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 212099981 is about 14563.6527354919. The cubic root of 212099981 is about 596.3669168766.

The spelling of 212099981 in words is "two hundred twelve million, ninety-nine thousand, nine hundred eighty-one".