20811618 has 24 divisors (see below), whose sum is σ = 46647900. Its totient is φ = 6697824.

The previous prime is 20811611. The next prime is 20811653. The reversal of 20811618 is 81611802.

It can be written as a sum of positive squares in 2 ways, for example, as 20766249 + 45369 = 4557^2 + 213^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20811591 and 20811600.

It is not an unprimeable number, because it can be changed into a prime (20811611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19413 + ... + 20456.

Almost surely, 2^20811618 is an apocalyptic number.

20811618 is an abundant number, since it is smaller than the sum of its proper divisors (25836282).

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

20811618 is a wasteful number, since it uses less digits than its factorization.

20811618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39906 (or 39903 counting only the distinct ones).

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

The square root of 20811618 is about 4561.9752300950. The cubic root of 20811618 is about 275.0649675706.

The spelling of 20811618 in words is "twenty million, eight hundred eleven thousand, six hundred eighteen".