2191381 has 4 divisors (see below), whose sum is σ = 2219200. Its totient is φ = 2163564.

The previous prime is 2191373. The next prime is 2191393. The reversal of 2191381 is 1831912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2191381 - 2³ = 2191373 is a prime.

It is a super-2 number, since 2×2191381² = 9604301374322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2191331) 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, 13791 + ... + 13948.

It is an arithmetic number, because the mean of its divisors is an integer number (554800).

2^2191381 is an apocalyptic number.

It is an amenable number.

2191381 is a deficient number, since it is larger than the sum of its proper divisors (27819).

2191381 is an equidigital number, since it uses as much as digits as its factorization.

2191381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27818.

The product of its digits is 432, while the sum is 25.

The square root of 2191381 is about 1480.3313818196. The cubic root of 2191381 is about 129.8890769790.

It can be divided in two parts, 219 and 1381, that added together give a square (1600 = 40²).

The spelling of 2191381 in words is "two million, one hundred ninety-one thousand, three hundred eighty-one".