21501445680 has 640 divisors, whose sum is σ = 87774382080. Its totient is φ = 4769280000.

The previous prime is 21501445619. The next prime is 21501445681. The reversal of 21501445680 is 8654410512.

It is a happy number.

21501445680 is a `hidden beast` number, since 2 + 1 + 50 + 1 + 44 + 568 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21501445681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 46640650 + ... + 46641110.

It is an arithmetic number, because the mean of its divisors is an integer number (137147472).

Almost surely, 2^21501445680 is an apocalyptic number.

21501445680 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 21501445680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43887191040).

21501445680 is an abundant number, since it is smaller than the sum of its proper divisors (66272936400).

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

21501445680 is a wasteful number, since it uses less digits than its factorization.

21501445680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658 (or 646 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

The spelling of 21501445680 in words is "twenty-one billion, five hundred one million, four hundred forty-five thousand, six hundred eighty".