2155811 has 8 divisors (see below), whose sum is σ = 2475264. Its totient is φ = 1839240.

The previous prime is 2155799. The next prime is 2155837. The reversal of 2155811 is 1185512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2155811 - 2¹⁴ = 2139427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2155841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1256 + ... + 2426.

It is an arithmetic number, because the mean of its divisors is an integer number (309408).

2^2155811 is an apocalyptic number.

2155811 is a deficient number, since it is larger than the sum of its proper divisors (319453).

2155811 is a wasteful number, since it uses less digits than its factorization.

2155811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1441.

The product of its digits is 400, while the sum is 23.

The square root of 2155811 is about 1468.2680273029. The cubic root of 2155811 is about 129.1824631854.

Subtracting from 2155811 its reverse (1185512), we obtain a cube (970299 = 99³).

The spelling of 2155811 in words is "two million, one hundred fifty-five thousand, eight hundred eleven".