20818161 has 64 divisors (see below), whose sum is σ = 39155200. Its totient is φ = 10637568.

The previous prime is 20818153. The next prime is 20818181. The reversal of 20818161 is 16181802.

It is not a de Polignac number, because 20818161 - 2³ = 20818153 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (20818121) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 90795 + ... + 91023.

It is an arithmetic number, because the mean of its divisors is an integer number (611800).

Almost surely, 2^20818161 is an apocalyptic number.

20818161 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20818161 is the 2886-th heptagonal number.

It is an amenable number.

20818161 is a deficient number, since it is larger than the sum of its proper divisors (18337039).

20818161 is a wasteful number, since it uses less digits than its factorization.

20818161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295 (or 289 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 20818161 is about 4562.6922973175. The cubic root of 20818161 is about 275.0937905980.

Adding to 20818161 its reverse (16181802), we get a palindrome (36999963).

The spelling of 20818161 in words is "twenty million, eight hundred eighteen thousand, one hundred sixty-one".