21985442028 has 144 divisors (see below), whose sum is σ = 61321408512. Its totient is φ = 6641157600.

The previous prime is 21985441999. The next prime is 21985442029. The reversal of 21985442028 is 82024458912.

21985442028 is a `hidden beast` number, since 219 + 8 + 5 + 4 + 420 + 2 + 8 = 666.

It is a super-2 number, since 2×21985442028² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21985442029) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 22184613 + ... + 22185603.

Almost surely, 2^21985442028 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21985442028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30660704256).

21985442028 is an abundant number, since it is smaller than the sum of its proper divisors (39335966484).

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

21985442028 is a wasteful number, since it uses less digits than its factorization.

21985442028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1497 (or 1470 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The spelling of 21985442028 in words is "twenty-one billion, nine hundred eighty-five million, four hundred forty-two thousand, twenty-eight".