21487684140 has 432 divisors, whose sum is σ = 76818557088. Its totient is φ = 4839284736.

The previous prime is 21487684139. The next prime is 21487684171. The reversal of 21487684140 is 4148678412.

21487684140 is a `hidden beast` number, since 21 + 487 + 6 + 8 + 4 + 140 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 19133619 + ... + 19134741.

It is an arithmetic number, because the mean of its divisors is an integer number (177820734).

Almost surely, 2^21487684140 is an apocalyptic number.

21487684140 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 21487684140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38409278544).

21487684140 is an abundant number, since it is smaller than the sum of its proper divisors (55330872948).

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

21487684140 is a wasteful number, since it uses less digits than its factorization.

21487684140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218 (or 1200 counting only the distinct ones).

The product of its (nonzero) digits is 344064, while the sum is 45.

The spelling of 21487684140 in words is "twenty-one billion, four hundred eighty-seven million, six hundred eighty-four thousand, one hundred forty".