21291230016 has 168 divisors, whose sum is σ = 69819072960. Its totient is φ = 6076809216.

The previous prime is 21291230011. The next prime is 21291230027. The reversal of 21291230016 is 61003219212.

It is a tau number, because it is divible by the number of its divisors (168).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291230011) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4904775 + ... + 4909113.

It is an arithmetic number, because the mean of its divisors is an integer number (415589720).

Almost surely, 2^21291230016 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 21291230016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34909536480).

21291230016 is an abundant number, since it is smaller than the sum of its proper divisors (48527842944).

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

21291230016 is a wasteful number, since it uses less digits than its factorization.

21291230016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5581 (or 5568 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

Adding to 21291230016 its reverse (61003219212), we get a palindrome (82294449228).

The spelling of 21291230016 in words is "twenty-one billion, two hundred ninety-one million, two hundred thirty thousand, sixteen".