21636012144 has 80 divisors (see below), whose sum is σ = 56896008224. Its totient is φ = 7083417600.

The previous prime is 21636012137. The next prime is 21636012161. The reversal of 21636012144 is 44121063612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 831654 + ... + 857274.

Almost surely, 2^21636012144 is an apocalyptic number.

21636012144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21636012144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28448004112).

21636012144 is an abundant number, since it is smaller than the sum of its proper divisors (35259996080).

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

21636012144 is a wasteful number, since it uses less digits than its factorization.

21636012144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25946 (or 25940 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

Adding to 21636012144 its reverse (44121063612), we get a palindrome (65757075756).

The spelling of 21636012144 in words is "twenty-one billion, six hundred thirty-six million, twelve thousand, one hundred forty-four".