213366781 has 2 divisors, whose sum is σ = 213366782. Its totient is φ = 213366780.

The previous prime is 213366773. The next prime is 213366851. The reversal of 213366781 is 187663312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156500100 + 56866681 = 12510^2 + 7541^2 .

It is a cyclic number.

It is not a de Polignac number, because 213366781 - 2³ = 213366773 is a prime.

It is a super-2 number, since 2×213366781² = 91050766468603922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 213366781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213366761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106683390 + 106683391.

It is an arithmetic number, because the mean of its divisors is an integer number (106683391).

Almost surely, 2^213366781 is an apocalyptic number.

It is an amenable number.

213366781 is a deficient number, since it is larger than the sum of its proper divisors (1).

213366781 is an equidigital number, since it uses as much as digits as its factorization.

213366781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 37.

The square root of 213366781 is about 14607.0798245234. The cubic root of 213366781 is about 597.5518588533.

The spelling of 213366781 in words is "two hundred thirteen million, three hundred sixty-six thousand, seven hundred eighty-one".