20021205618 has 30 divisors (see below), whose sum is σ = 44866366941. Its totient is φ = 6673134888.

The previous prime is 20021205601. The next prime is 20021205647. The reversal of 20021205618 is 81650212002.

It is a happy number.

20021205618 is a `hidden beast` number, since 2 + 0 + 0 + 21 + 20 + 5 + 618 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16257015009 + 3764190609 = 127503^2 + 61353^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=100053.

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

It is a junction number, because it is equal to n+sod(n) for n = 20021205591 and 20021205600.

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1795396 + ... + 1806512.

Almost surely, 2^20021205618 is an apocalyptic number.

20021205618 is an abundant number, since it is smaller than the sum of its proper divisors (24845161323).

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

20021205618 is an frugal number, since it uses more digits than its factorization.

20021205618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22248 (or 11122 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The spelling of 20021205618 in words is "twenty billion, twenty-one million, two hundred five thousand, six hundred eighteen".