21316616640 has 224 divisors, whose sum is σ = 82037041920. Its totient is φ = 5167641600.

The previous prime is 21316616617. The next prime is 21316616641. The reversal of 21316616640 is 4661661312.

It is a happy number.

21316616640 is a `hidden beast` number, since 2 + 1 + 3 + 1 + 6 + 6 + 1 + 6 + 640 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21316616595 and 21316616604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21316616641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17106 + ... + 207185.

Almost surely, 2^21316616640 is an apocalyptic number.

21316616640 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 21316616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41018520960).

21316616640 is an abundant number, since it is smaller than the sum of its proper divisors (60720425280).

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

21316616640 is a wasteful number, since it uses less digits than its factorization.

21316616640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224328 (or 224312 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The spelling of 21316616640 in words is "twenty-one billion, three hundred sixteen million, six hundred sixteen thousand, six hundred forty".