213660991 has 2 divisors, whose sum is σ = 213660992. Its totient is φ = 213660990.

The previous prime is 213660911. The next prime is 213661031. The reversal of 213660991 is 199066312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 213660991 - 2¹³ = 213652799 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 213660991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213660901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106830495 + 106830496.

It is an arithmetic number, because the mean of its divisors is an integer number (106830496).

Almost surely, 2^213660991 is an apocalyptic number.

213660991 is a deficient number, since it is larger than the sum of its proper divisors (1).

213660991 is an equidigital number, since it uses as much as digits as its factorization.

213660991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 213660991 is about 14617.1471566787. The cubic root of 213660991 is about 597.8263861057.

The spelling of 213660991 in words is "two hundred thirteen million, six hundred sixty thousand, nine hundred ninety-one".