212089781 has 2 divisors, whose sum is σ = 212089782. Its totient is φ = 212089780.

The previous prime is 212089777. The next prime is 212089811. The reversal of 212089781 is 187980212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 202066225 + 10023556 = 14215^2 + 3166^2 .

It is a cyclic number.

It is not a de Polignac number, because 212089781 - 2² = 212089777 is a prime.

It is a super-2 number, since 2×212089781² = 89964150409255922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212089181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106044890 + 106044891.

It is an arithmetic number, because the mean of its divisors is an integer number (106044891).

Almost surely, 2^212089781 is an apocalyptic number.

It is an amenable number.

212089781 is a deficient number, since it is larger than the sum of its proper divisors (1).

212089781 is an equidigital number, since it uses as much as digits as its factorization.

212089781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 212089781 is about 14563.3025444094. The cubic root of 212089781 is about 596.3573568568.

It can be divided in two parts, 21 and 2089781, that added together give a palindrome (2089802).

The spelling of 212089781 in words is "two hundred twelve million, eighty-nine thousand, seven hundred eighty-one".