21508338240 has 168 divisors, whose sum is σ = 76719988800. Its totient is φ = 5735536128.

The previous prime is 21508338227. The next prime is 21508338251. The reversal of 21508338240 is 4283380512.

21508338240 is a `hidden beast` number, since 2 + 1 + 508 + 33 + 82 + 40 = 666.

It is a super-2 number, since 2×21508338240² (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 = 21508338195 and 21508338204.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 60540 + ... + 216059.

It is an arithmetic number, because the mean of its divisors is an integer number (456666600).

Almost surely, 2^21508338240 is an apocalyptic number.

21508338240 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 21508338240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38359994400).

21508338240 is an abundant number, since it is smaller than the sum of its proper divisors (55211650560).

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

21508338240 is an equidigital number, since it uses as much as digits as its factorization.

21508338240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276631 (or 276609 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The spelling of 21508338240 in words is "twenty-one billion, five hundred eight million, three hundred thirty-eight thousand, two hundred forty".