21216403226365 has 8 divisors (see below), whose sum is σ = 25459741118520. Its totient is φ = 16973084416512.

The previous prime is 21216403226321. The next prime is 21216403226407. The reversal of 21216403226365 is 56362230461212.

It can be written as a sum of positive squares in 4 ways, for example, as 563913887364 + 20652489339001 = 750942^2 + 4544501^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21216403226365 - 2⁷ = 21216403226237 is a prime.

It is a super-2 number, since 2×21216403226365² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2198460 + ... + 6875029.

It is an arithmetic number, because the mean of its divisors is an integer number (3182467639815).

Almost surely, 2^{21216403226365} is an apocalyptic number.

It is an amenable number.

21216403226365 is a deficient number, since it is larger than the sum of its proper divisors (4243337892155).

21216403226365 is an equidigital number, since it uses as much as digits as its factorization.

21216403226365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9541151.

The product of its (nonzero) digits is 622080, while the sum is 43.

Adding to 21216403226365 its reverse (56362230461212), we get a palindrome (77578633687577).

The spelling of 21216403226365 in words is "twenty-one trillion, two hundred sixteen billion, four hundred three million, two hundred twenty-six thousand, three hundred sixty-five".