21218218365 has 32 divisors (see below), whose sum is σ = 35785451520. Its totient is φ = 10705932864.

The previous prime is 21218218363. The next prime is 21218218369. The reversal of 21218218365 is 56381281212.

It is not a de Polignac number, because 21218218365 - 2¹ = 21218218363 is a prime.

It is a super-3 number, since 3×21218218365³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21218218363) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 155992 + ... + 258398.

It is an arithmetic number, because the mean of its divisors is an integer number (1118295360).

Almost surely, 2^21218218365 is an apocalyptic number.

It is an amenable number.

21218218365 is a deficient number, since it is larger than the sum of its proper divisors (14567233155).

21218218365 is a wasteful number, since it uses less digits than its factorization.

21218218365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103161.

The product of its digits is 46080, while the sum is 39.

Adding to 21218218365 its reverse (56381281212), we get a palindrome (77599499577).

The spelling of 21218218365 in words is "twenty-one billion, two hundred eighteen million, two hundred eighteen thousand, three hundred sixty-five".