21161616016 has 80 divisors (see below), whose sum is σ = 45407093760. Its totient is φ = 9514920960.

The previous prime is 21161616011. The next prime is 21161616017. The reversal of 21161616016 is 61061616112.

It is not an unprimeable number, because it can be changed into a prime (21161616011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 438225 + ... + 484111.

It is an arithmetic number, because the mean of its divisors is an integer number (567588672).

Almost surely, 2^21161616016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21161616016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22703546880).

21161616016 is an abundant number, since it is smaller than the sum of its proper divisors (24245477744).

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

21161616016 is a wasteful number, since it uses less digits than its factorization.

21161616016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45992 (or 45986 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The spelling of 21161616016 in words is "twenty-one billion, one hundred sixty-one million, six hundred sixteen thousand, sixteen".