21161002251216 has 40 divisors (see below), whose sum is σ = 55324548064800. Its totient is φ = 6968683470976.

The previous prime is 21161002251173. The next prime is 21161002251241. The reversal of 21161002251216 is 61215220016112.

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, 2655744291 + ... + 2655752258.

It is an arithmetic number, because the mean of its divisors is an integer number (1383113701620).

Almost surely, 2^{21161002251216} is an apocalyptic number.

It is an amenable number.

21161002251216 is an abundant number, since it is smaller than the sum of its proper divisors (34163545813584).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21161002251216 is a wasteful number, since it uses less digits than its factorization.

21161002251216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5311496643 (or 5311496637 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

Adding to 21161002251216 its reverse (61215220016112), we get a palindrome (82376222267328).

The spelling of 21161002251216 in words is "twenty-one trillion, one hundred sixty-one billion, two million, two hundred fifty-one thousand, two hundred sixteen".