2151811 has 4 divisors (see below), whose sum is σ = 2245392. Its totient is φ = 2058232.

The previous prime is 2151791. The next prime is 2151817. The reversal of 2151811 is 1181512.

It is a happy number.

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 2151811 - 2⁷ = 2151683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2151817) 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, 46756 + ... + 46801.

It is an arithmetic number, because the mean of its divisors is an integer number (561348).

2^2151811 is an apocalyptic number.

2151811 is a deficient number, since it is larger than the sum of its proper divisors (93581).

2151811 is an equidigital number, since it uses as much as digits as its factorization.

2151811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93580.

The product of its digits is 80, while the sum is 19.

The square root of 2151811 is about 1466.9052457470. The cubic root of 2151811 is about 129.1025165093.

Subtracting from 2151811 its reverse (1181512), we obtain a cube (970299 = 99³).

The spelling of 2151811 in words is "two million, one hundred fifty-one thousand, eight hundred eleven".