2157791 has 6 divisors (see below), whose sum is σ = 2256240. Its totient is φ = 2063468.

The previous prime is 2157787. The next prime is 2157797. The reversal of 2157791 is 1977512.

It is not a de Polignac number, because 2157791 - 2² = 2157787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157797) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1511 + ... + 2568.

It is an arithmetic number, because the mean of its divisors is an integer number (376040).

2^2157791 is an apocalyptic number.

2157791 is a deficient number, since it is larger than the sum of its proper divisors (98449).

2157791 is an equidigital number, since it uses as much as digits as its factorization.

2157791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4125 (or 4102 counting only the distinct ones).

The product of its digits is 4410, while the sum is 32.

The square root of 2157791 is about 1468.9421363689. The cubic root of 2157791 is about 129.2220002026. Note that the first 3 decimals are identical.

The spelling of 2157791 in words is "two million, one hundred fifty-seven thousand, seven hundred ninety-one".