21285868944 has 80 divisors (see below), whose sum is σ = 56306203712. Its totient is φ = 6925492224.

The previous prime is 21285868943. The next prime is 21285868973. The reversal of 21285868944 is 44986858212.

It is a super-2 number, since 2×21285868944² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21285868943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4160532 + ... + 4165644.

Almost surely, 2^21285868944 is an apocalyptic number.

21285868944 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 21285868944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28153101856).

21285868944 is an abundant number, since it is smaller than the sum of its proper divisors (35020334768).

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

21285868944 is a wasteful number, since it uses less digits than its factorization.

21285868944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7184 (or 7178 counting only the distinct ones).

The product of its digits is 8847360, while the sum is 57.

The spelling of 21285868944 in words is "twenty-one billion, two hundred eighty-five million, eight hundred sixty-eight thousand, nine hundred forty-four".