20721447180 has 432 divisors, whose sum is σ = 75384429120. Its totient is φ = 4512568320.

The previous prime is 20721447179. The next prime is 20721447217. The reversal of 20721447180 is 8174412702.

20721447180 is a `hidden beast` number, since 207 + 2 + 1 + 447 + 1 + 8 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 131983662 + ... + 131983818.

Almost surely, 2^20721447180 is an apocalyptic number.

20721447180 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 20721447180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37692214560).

20721447180 is an abundant number, since it is smaller than the sum of its proper divisors (54662981940).

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

20721447180 is a wasteful number, since it uses less digits than its factorization.

20721447180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350 (or 314 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

Adding to 20721447180 its reverse (8174412702), we get a palindrome (28895859882).

The spelling of 20721447180 in words is "twenty billion, seven hundred twenty-one million, four hundred forty-seven thousand, one hundred eighty".