213381991 has 4 divisors (see below), whose sum is σ = 213485184. Its totient is φ = 213278800.

The previous prime is 213381947. The next prime is 213382003. The reversal of 213381991 is 199183312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 213381991 - 2⁷ = 213381863 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 213381991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213381941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48430 + ... + 52651.

It is an arithmetic number, because the mean of its divisors is an integer number (53371296).

Almost surely, 2^213381991 is an apocalyptic number.

213381991 is a deficient number, since it is larger than the sum of its proper divisors (103193).

213381991 is a wasteful number, since it uses less digits than its factorization.

213381991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103192.

The product of its digits is 11664, while the sum is 37.

The square root of 213381991 is about 14607.6004531887. The cubic root of 213381991 is about 597.5660574831.

The spelling of 213381991 in words is "two hundred thirteen million, three hundred eighty-one thousand, nine hundred ninety-one".