21781020576 has 144 divisors (see below), whose sum is σ = 70010710560. Its totient is φ = 5895590400.

The previous prime is 21781020533. The next prime is 21781020589. The reversal of 21781020576 is 67502018712.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

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, 32475 + ... + 211226.

It is an arithmetic number, because the mean of its divisors is an integer number (486185490).

Almost surely, 2^21781020576 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 21781020576, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35005355280).

21781020576 is an abundant number, since it is smaller than the sum of its proper divisors (48229689984).

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

21781020576 is a wasteful number, since it uses less digits than its factorization.

21781020576 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243747 (or 243732 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 39.

The spelling of 21781020576 in words is "twenty-one billion, seven hundred eighty-one million, twenty thousand, five hundred seventy-six".