217578043620 has 768 divisors, whose sum is σ = 858370867200. Its totient is φ = 44608734720.

The previous prime is 217578043607. The next prime is 217578043681. The reversal of 217578043620 is 26340875712.

217578043620 is a `hidden beast` number, since 2 + 17 + 5 + 7 + 8 + 0 + 4 + 3 + 620 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 176748405 + ... + 176749635.

It is an arithmetic number, because the mean of its divisors is an integer number (1117670400).

Almost surely, 2^217578043620 is an apocalyptic number.

217578043620 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 217578043620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (429185433600).

217578043620 is an abundant number, since it is smaller than the sum of its proper divisors (640792823580).

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

217578043620 is a wasteful number, since it uses less digits than its factorization.

217578043620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1405 (or 1397 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 45.

The spelling of 217578043620 in words is "two hundred seventeen billion, five hundred seventy-eight million, forty-three thousand, six hundred twenty".