2157811 has 6 divisors (see below), whose sum is σ = 2278140. Its totient is φ = 2038176.

The previous prime is 2157797. The next prime is 2157821. The reversal of 2157811 is 1187512.

It is not a de Polignac number, because 2157811 - 2¹³ = 2149619 is a prime.

It is a super-2 number, since 2×2157811² = 9312296623442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2157821) 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, 6235 + ... + 6571.

It is an arithmetic number, because the mean of its divisors is an integer number (379690).

2^2157811 is an apocalyptic number.

2157811 is a deficient number, since it is larger than the sum of its proper divisors (120329).

2157811 is an frugal number, since it uses more digits than its factorization.

2157811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 693 (or 356 counting only the distinct ones).

The product of its digits is 560, while the sum is 25.

The square root of 2157811 is about 1468.9489439732. The cubic root of 2157811 is about 129.2223994430. Note that the first 3 decimals are identical.

Subtracting from 2157811 its reverse (1187512), we obtain a cube (970299 = 99³).

The spelling of 2157811 in words is "two million, one hundred fifty-seven thousand, eight hundred eleven".