21216420365165 has 64 divisors (see below), whose sum is σ = 26981411143680. Its totient is φ = 15984224256000.

The previous prime is 21216420365143. The next prime is 21216420365191. The reversal of 21216420365165 is 56156302461212.

It is not a de Polignac number, because 21216420365165 - 2¹² = 21216420361069 is a prime.

It is a super-2 number, since 2×21216420365165² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 932537540 + ... + 932560290.

It is an arithmetic number, because the mean of its divisors is an integer number (421584549120).

Almost surely, 2^{21216420365165} is an apocalyptic number.

It is an amenable number.

21216420365165 is a deficient number, since it is larger than the sum of its proper divisors (5764990778515).

21216420365165 is a wasteful number, since it uses less digits than its factorization.

21216420365165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23402.

The product of its (nonzero) digits is 518400, while the sum is 44.

The spelling of 21216420365165 in words is "twenty-one trillion, two hundred sixteen billion, four hundred twenty million, three hundred sixty-five thousand, one hundred sixty-five".