2157811818 has 16 divisors (see below), whose sum is σ = 4374742656. Its totient is φ = 709417440.

The previous prime is 2157811813. The next prime is 2157811829. The reversal of 2157811818 is 8181187512.

It is a self number, because there is not a number n which added to its sum of digits gives 2157811818.

It is not an unprimeable number, because it can be changed into a prime (2157811813) 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 7 ways as a sum of consecutive naturals, for example, 2462818 + ... + 2463693.

It is an arithmetic number, because the mean of its divisors is an integer number (273421416).

Almost surely, 2^2157811818 is an apocalyptic number.

2157811818 is an abundant number, since it is smaller than the sum of its proper divisors (2216930838).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2157811818 is a wasteful number, since it uses less digits than its factorization.

2157811818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4926589.

The product of its digits is 35840, while the sum is 42.

The square root of 2157811818 is about 46452.2530992846. The cubic root of 2157811818 is about 1292.2241577191.

The spelling of 2157811818 in words is "two billion, one hundred fifty-seven million, eight hundred eleven thousand, eight hundred eighteen".