21665730240 has 1008 divisors, whose sum is σ = 100253316384. Its totient is φ = 4231987200.

The previous prime is 21665730211. The next prime is 21665730269. The reversal of 21665730240 is 4203756612.

21665730240 is a `hidden beast` number, since 2 + 1 + 66 + 573 + 0 + 24 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21665730211) and next prime (21665730269).

It is a tau number, because it is divible by the number of its divisors (1008).

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 = 21665730195 and 21665730204.

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, 26389030 + ... + 26389850.

Almost surely, 2^21665730240 is an apocalyptic number.

21665730240 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 21665730240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50126658192).

21665730240 is an abundant number, since it is smaller than the sum of its proper divisors (78587586144).

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

21665730240 is a wasteful number, since it uses less digits than its factorization.

21665730240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 886 (or 866 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21665730240 in words is "twenty-one billion, six hundred sixty-five million, seven hundred thirty thousand, two hundred forty".