21489994944 has 252 divisors, whose sum is σ = 67951276848. Its totient is φ = 6488570880.

The previous prime is 21489994943. The next prime is 21489994991. The reversal of 21489994944 is 44949998412.

21489994944 is a `hidden beast` number, since 21 + 489 + 9 + 94 + 9 + 44 = 666.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21489994943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 35056782 + ... + 35057394.

It is an arithmetic number, because the mean of its divisors is an integer number (269647924).

Almost surely, 2^21489994944 is an apocalyptic number.

21489994944 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 21489994944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33975638424).

21489994944 is an abundant number, since it is smaller than the sum of its proper divisors (46461281904).

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

21489994944 is a wasteful number, since it uses less digits than its factorization.

21489994944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1156 (or 1132 counting only the distinct ones).

The product of its digits is 26873856, while the sum is 63.

The spelling of 21489994944 in words is "twenty-one billion, four hundred eighty-nine million, nine hundred ninety-four thousand, nine hundred forty-four".