2191851 has 6 divisors (see below), whose sum is σ = 3166020. Its totient is φ = 1461228.

The previous prime is 2191823. The next prime is 2191873. The reversal of 2191851 is 1581912.

It is not a de Polignac number, because 2191851 - 2⁷ = 2191723 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2191811) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 121761 + ... + 121778.

It is an arithmetic number, because the mean of its divisors is an integer number (527670).

2^2191851 is an apocalyptic number.

2191851 is a deficient number, since it is larger than the sum of its proper divisors (974169).

2191851 is a wasteful number, since it uses less digits than its factorization.

2191851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243545 (or 243542 counting only the distinct ones).

The product of its digits is 720, while the sum is 27.

The square root of 2191851 is about 1480.4901215476. The cubic root of 2191851 is about 129.8983623722.

The spelling of 2191851 in words is "two million, one hundred ninety-one thousand, eight hundred fifty-one".