217621978375 has 8 divisors (see below), whose sum is σ = 271592229168. Its totient is φ = 174097582600.

The previous prime is 217621978351. The next prime is 217621978393. The reversal of 217621978375 is 573879126712.

It is not a de Polignac number, because 217621978375 - 2¹³ = 217621970183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 870487789 + ... + 870488038.

It is an arithmetic number, because the mean of its divisors is an integer number (33949028646).

Almost surely, 2^217621978375 is an apocalyptic number.

217621978375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

217621978375 is a deficient number, since it is larger than the sum of its proper divisors (53970250793).

217621978375 is an equidigital number, since it uses as much as digits as its factorization.

217621978375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740975842 (or 1740975832 counting only the distinct ones).

The product of its digits is 8890560, while the sum is 58.

The spelling of 217621978375 in words is "two hundred seventeen billion, six hundred twenty-one million, nine hundred seventy-eight thousand, three hundred seventy-five".