21204126413365 has 16 divisors (see below), whose sum is σ = 30610468206720. Its totient is φ = 13774710692160.

The previous prime is 21204126413363. The next prime is 21204126413387. The reversal of 21204126413365 is 56331462140212.

It is not a de Polignac number, because 21204126413365 - 2¹ = 21204126413363 is a prime.

It is a super-2 number, since 2×21204126413365² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204126413363) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15942951526 + ... + 15942952855.

It is an arithmetic number, because the mean of its divisors is an integer number (1913154262920).

Almost surely, 2^{21204126413365} is an apocalyptic number.

It is an amenable number.

21204126413365 is a deficient number, since it is larger than the sum of its proper divisors (9406341793355).

21204126413365 is a wasteful number, since it uses less digits than its factorization.

21204126413365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31885904412.

The product of its (nonzero) digits is 207360, while the sum is 40.

Adding to 21204126413365 its reverse (56331462140212), we get a palindrome (77535588553577).

The spelling of 21204126413365 in words is "twenty-one trillion, two hundred four billion, one hundred twenty-six million, four hundred thirteen thousand, three hundred sixty-five".