213717991 has 2 divisors, whose sum is σ = 213717992. Its totient is φ = 213717990.

The previous prime is 213717979. The next prime is 213717997. The reversal of 213717991 is 199717312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 213717991 - 2²⁵ = 180163559 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213717997) 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, 106858995 + 106858996.

It is an arithmetic number, because the mean of its divisors is an integer number (106858996).

Almost surely, 2^213717991 is an apocalyptic number.

213717991 is a deficient number, since it is larger than the sum of its proper divisors (1).

213717991 is an equidigital number, since it uses as much as digits as its factorization.

213717991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23814, while the sum is 40.

The square root of 213717991 is about 14619.0967915258. The cubic root of 213717991 is about 597.8795436398.

The spelling of 213717991 in words is "two hundred thirteen million, seven hundred seventeen thousand, nine hundred ninety-one".