21761247816 has 384 divisors, whose sum is σ = 76523765760. Its totient is φ = 5421427200.

The previous prime is 21761247797. The next prime is 21761247829. The reversal of 21761247816 is 61874216712.

21761247816 is a `hidden beast` number, since 2 + 17 + 612 + 4 + 7 + 8 + 16 = 666.

It is a nude number because it is divisible by every one of its digits.

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 95 ways as a sum of consecutive naturals, for example, 21826230 + ... + 21827226.

It is an arithmetic number, because the mean of its divisors is an integer number (199280640).

Almost surely, 2^21761247816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21761247816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38261882880).

21761247816 is an abundant number, since it is smaller than the sum of its proper divisors (54762517944).

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

21761247816 is a wasteful number, since it uses less digits than its factorization.

21761247816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1185 (or 1178 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The spelling of 21761247816 in words is "twenty-one billion, seven hundred sixty-one million, two hundred forty-seven thousand, eight hundred sixteen".