213991866 has 24 divisors (see below), whose sum is σ = 505799424. Its totient is φ = 64845960.

The previous prime is 213991861. The next prime is 213991891. The reversal of 213991866 is 668199312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (213991861) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 540186 + ... + 540581.

It is an arithmetic number, because the mean of its divisors is an integer number (21074976).

Almost surely, 2^213991866 is an apocalyptic number.

213991866 is an abundant number, since it is smaller than the sum of its proper divisors (291807558).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

213991866 is a wasteful number, since it uses less digits than its factorization.

213991866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1080786 (or 1080783 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 213991866 is about 14628.4608212894. The cubic root of 213991866 is about 598.1348245423.

The spelling of 213991866 in words is "two hundred thirteen million, nine hundred ninety-one thousand, eight hundred sixty-six".