217121764903680 has 1152 divisors, whose sum is σ = 899885602990080. Its totient is φ = 43326229708800.

The previous prime is 217121764903651. The next prime is 217121764903759. The reversal of 217121764903680 is 86309467121712.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a self number, because there is not a number n which added to its sum of digits gives 217121764903680.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3990228154 + ... + 3990282566.

It is an arithmetic number, because the mean of its divisors is an integer number (781150697040).

Almost surely, 2^{217121764903680} is an apocalyptic number.

217121764903680 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 217121764903680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (449942801495040).

217121764903680 is an abundant number, since it is smaller than the sum of its proper divisors (682763838086400).

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

217121764903680 is a wasteful number, since it uses less digits than its factorization.

217121764903680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55077 (or 55063 counting only the distinct ones).

The product of its (nonzero) digits is 6096384, while the sum is 57.

The spelling of 217121764903680 in words is "two hundred seventeen trillion, one hundred twenty-one billion, seven hundred sixty-four million, nine hundred three thousand, six hundred eighty".