21646326240 has 648 divisors, whose sum is σ = 94304515032. Its totient is φ = 4471004160.

The previous prime is 21646326239. The next prime is 21646326269. The reversal of 21646326240 is 4262364612.

21646326240 is a `hidden beast` number, since 2 + 1 + 646 + 3 + 2 + 6 + 2 + 4 + 0 = 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 = 21646326195 and 21646326204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 129618637 + ... + 129618803.

It is an arithmetic number, because the mean of its divisors is an integer number (145531659).

Almost surely, 2^21646326240 is an apocalyptic number.

21646326240 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 21646326240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47152257516).

21646326240 is an abundant number, since it is smaller than the sum of its proper divisors (72658188792).

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

21646326240 is a wasteful number, since it uses less digits than its factorization.

21646326240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 380 (or 195 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The spelling of 21646326240 in words is "twenty-one billion, six hundred forty-six million, three hundred twenty-six thousand, two hundred forty".