21755772144 has 120 divisors (see below), whose sum is σ = 61404142800. Its totient is φ = 7190470656.

The previous prime is 21755772119. The next prime is 21755772161. The reversal of 21755772144 is 44127755712.

It is a happy number.

21755772144 is a `hidden beast` number, since 2 + 1 + 75 + 577 + 2 + 1 + 4 + 4 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21755772144.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9698287 + ... + 9700529.

It is an arithmetic number, because the mean of its divisors is an integer number (511701190).

Almost surely, 2^21755772144 is an apocalyptic number.

21755772144 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 21755772144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30702071400).

21755772144 is an abundant number, since it is smaller than the sum of its proper divisors (39648370656).

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

21755772144 is a wasteful number, since it uses less digits than its factorization.

21755772144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2799 (or 2790 counting only the distinct ones).

The product of its digits is 548800, while the sum is 45.

The spelling of 21755772144 in words is "twenty-one billion, seven hundred fifty-five million, seven hundred seventy-two thousand, one hundred forty-four".