2157808 has 20 divisors (see below), whose sum is σ = 4212280. Its totient is φ = 1070784.

The previous prime is 2157797. The next prime is 2157821. The reversal of 2157808 is 8087512.

It is a super-2 number, since 2×2157808² = 9312270729728, which contains 22 as substring.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 2157808.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2083 + ... + 2941.

It is an arithmetic number, because the mean of its divisors is an integer number (210614).

2^2157808 is an apocalyptic number.

It is an amenable number.

2157808 is a deficient number, since it is larger than the sum of its proper divisors (2054472).

2157808 is a wasteful number, since it uses less digits than its factorization.

2157808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024 (or 1018 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 2157808 is about 1468.9479228346. The cubic root of 2157808 is about 129.2223395571. Note that the first 3 decimals are identical.

The spelling of 2157808 in words is "two million, one hundred fifty-seven thousand, eight hundred eight".