21516256446221 has 8 divisors (see below), whose sum is σ = 21531037089120. Its totient is φ = 21501477267408.

The previous prime is 21516256446163. The next prime is 21516256446233. The reversal of 21516256446221 is 12264465261512.

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 21516256446221 - 2¹⁰ = 21516256445197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516256445221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29893250 + ... + 30604556.

It is an arithmetic number, because the mean of its divisors is an integer number (2691379636140).

Almost surely, 2^{21516256446221} is an apocalyptic number.

It is an amenable number.

21516256446221 is a deficient number, since it is larger than the sum of its proper divisors (14780642899).

21516256446221 is a wasteful number, since it uses less digits than its factorization.

21516256446221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 732043.

The product of its digits is 1382400, while the sum is 47.

The spelling of 21516256446221 in words is "twenty-one trillion, five hundred sixteen billion, two hundred fifty-six million, four hundred forty-six thousand, two hundred twenty-one".