21216420365065 has 16 divisors (see below), whose sum is σ = 25738425554688. Its totient is φ = 16787543302656.

The previous prime is 21216420365057. The next prime is 21216420365131. The reversal of 21216420365065 is 56056302461212.

It is a cyclic number.

It is not a de Polignac number, because 21216420365065 - 2³ = 21216420365057 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13049427 + ... + 14584936.

It is an arithmetic number, because the mean of its divisors is an integer number (1608651597168).

Almost surely, 2^{21216420365065} is an apocalyptic number.

It is an amenable number.

21216420365065 is a deficient number, since it is larger than the sum of its proper divisors (4522005189623).

21216420365065 is a wasteful number, since it uses less digits than its factorization.

21216420365065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27636048.

The product of its (nonzero) digits is 518400, while the sum is 43.

The spelling of 21216420365065 in words is "twenty-one trillion, two hundred sixteen billion, four hundred twenty million, three hundred sixty-five thousand, sixty-five".