21118401007665 has 64 divisors (see below), whose sum is σ = 36483813821952. Its totient is φ = 10369562112000.

The previous prime is 21118401007621. The next prime is 21118401007727. The reversal of 21118401007665 is 56670010481112.

It is not a de Polignac number, because 21118401007665 - 2¹³ = 21118400999473 is a prime.

It is a super-2 number, since 2×21118401007665² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1280904052 + ... + 1280920538.

It is an arithmetic number, because the mean of its divisors is an integer number (570059590968).

Almost surely, 2^{21118401007665} is an apocalyptic number.

It is an amenable number.

21118401007665 is a deficient number, since it is larger than the sum of its proper divisors (15365412814287).

21118401007665 is a wasteful number, since it uses less digits than its factorization.

21118401007665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33290.

The product of its (nonzero) digits is 80640, while the sum is 42.

Adding to 21118401007665 its reverse (56670010481112), we get a palindrome (77788411488777).

The spelling of 21118401007665 in words is "twenty-one trillion, one hundred eighteen billion, four hundred one million, seven thousand, six hundred sixty-five".