21791646240 has 768 divisors, whose sum is σ = 89413632000. Its totient is φ = 4335648768.

The previous prime is 21791646223. The next prime is 21791646287. The reversal of 21791646240 is 4264619712.

It is a super-2 number, since 2×21791646240² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 21791646192 and 21791646201.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 109505661 + ... + 109505859.

It is an arithmetic number, because the mean of its divisors is an integer number (116424000).

Almost surely, 2^21791646240 is an apocalyptic number.

21791646240 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 21791646240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44706816000).

21791646240 is an abundant number, since it is smaller than the sum of its proper divisors (67621985760).

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

21791646240 is a wasteful number, since it uses less digits than its factorization.

21791646240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369 (or 361 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 42.

The spelling of 21791646240 in words is "twenty-one billion, seven hundred ninety-one million, six hundred forty-six thousand, two hundred forty".