21683628720 has 480 divisors, whose sum is σ = 81894758400. Its totient is φ = 5300370432.

The previous prime is 21683628689. The next prime is 21683628721. The reversal of 21683628720 is 2782638612.

21683628720 is a `hidden beast` number, since 2 + 16 + 8 + 3 + 628 + 7 + 2 + 0 = 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 Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21683628721) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 60399901 + ... + 60400259.

It is an arithmetic number, because the mean of its divisors is an integer number (170614080).

Almost surely, 2^21683628720 is an apocalyptic number.

21683628720 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 21683628720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40947379200).

21683628720 is an abundant number, since it is smaller than the sum of its proper divisors (60211129680).

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

21683628720 is a wasteful number, since it uses less digits than its factorization.

21683628720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639 (or 621 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 21683628720 in words is "twenty-one billion, six hundred eighty-three million, six hundred twenty-eight thousand, seven hundred twenty".