21201751917648 has 320 divisors, whose sum is σ = 64864160332800. Its totient is φ = 6619732439040.

The previous prime is 21201751917631. The next prime is 21201751917707. The reversal of 21201751917648 is 84671915710212.

21201751917648 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 17 + 519 + 1 + 76 + 48 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 21201751917594 and 21201751917603.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 55597161 + ... + 55977207.

It is an arithmetic number, because the mean of its divisors is an integer number (202700501040).

Almost surely, 2^{21201751917648} 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 21201751917648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32432080166400).

21201751917648 is an abundant number, since it is smaller than the sum of its proper divisors (43662408415152).

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

21201751917648 is a wasteful number, since it uses less digits than its factorization.

21201751917648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 380227 (or 380215 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 54.

The spelling of 21201751917648 in words is "twenty-one trillion, two hundred one billion, seven hundred fifty-one million, nine hundred seventeen thousand, six hundred forty-eight".