21608216640 has 896 divisors, whose sum is σ = 86026752000. Its totient is φ = 5080154112.

The previous prime is 21608216611. The next prime is 21608216711. The reversal of 21608216640 is 4661280612.

21608216640 is a `hidden beast` number, since 2 + 1 + 6 + 0 + 8 + 2 + 1 + 6 + 640 = 666.

It is a super-2 number, since 2×21608216640² (a number of 21 digits) contains 22 as substring.

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 = 21608216595 and 21608216604.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 222765072 + ... + 222765168.

It is an arithmetic number, because the mean of its divisors is an integer number (96012000).

Almost surely, 2^21608216640 is an apocalyptic number.

21608216640 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 21608216640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43013376000).

21608216640 is an abundant number, since it is smaller than the sum of its proper divisors (64418535360).

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

21608216640 is a wasteful number, since it uses less digits than its factorization.

21608216640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The spelling of 21608216640 in words is "twenty-one billion, six hundred eight million, two hundred sixteen thousand, six hundred forty".