213031891 has 4 divisors (see below), whose sum is σ = 213414912. Its totient is φ = 212648872.

The previous prime is 213031853. The next prime is 213031909. The reversal of 213031891 is 198130312.

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 213031891 - 2²¹ = 210934739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (213031991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 190675 + ... + 191788.

It is an arithmetic number, because the mean of its divisors is an integer number (53353728).

Almost surely, 2^213031891 is an apocalyptic number.

213031891 is a deficient number, since it is larger than the sum of its proper divisors (383021).

213031891 is an equidigital number, since it uses as much as digits as its factorization.

213031891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 383020.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 213031891 is about 14595.6120460911. The cubic root of 213031891 is about 597.2390658170.

The spelling of 213031891 in words is "two hundred thirteen million, thirty-one thousand, eight hundred ninety-one".