21144145440 has 288 divisors, whose sum is σ = 76691313216. Its totient is φ = 4855633920.

The previous prime is 21144145439. The next prime is 21144145481. The reversal of 21144145440 is 4454144112.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21144145398 and 21144145407.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 1900534 + ... + 1911626.

It is an arithmetic number, because the mean of its divisors is an integer number (266289282).

Almost surely, 2^21144145440 is an apocalyptic number.

21144145440 is a gapful number since it is divisible by the number (20) 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 21144145440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38345656608).

21144145440 is an abundant number, since it is smaller than the sum of its proper divisors (55547167776).

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

21144145440 is a wasteful number, since it uses less digits than its factorization.

21144145440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11160 (or 11133 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 30.

Adding to 21144145440 its reverse (4454144112), we get a palindrome (25598289552).

The spelling of 21144145440 in words is "twenty-one billion, one hundred forty-four million, one hundred forty-five thousand, four hundred forty".