21945485680 has 20 divisors (see below), whose sum is σ = 51023254392. Its totient is φ = 8778194240.

The previous prime is 21945485647. The next prime is 21945485689. The reversal of 21945485680 is 8658454912.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945485689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 137159206 + ... + 137159365.

Almost surely, 2^21945485680 is an apocalyptic number.

21945485680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21945485680 is an abundant number, since it is smaller than the sum of its proper divisors (29077768712).

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

21945485680 is a wasteful number, since it uses less digits than its factorization.

21945485680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274318584 (or 274318578 counting only the distinct ones).

The product of its (nonzero) digits is 2764800, while the sum is 52.

The spelling of 21945485680 in words is "twenty-one billion, nine hundred forty-five million, four hundred eighty-five thousand, six hundred eighty".