216815853870 has 768 divisors, whose sum is σ = 776787148800. Its totient is φ = 41688069120.

The previous prime is 216815853833. The next prime is 216815853871. The reversal of 216815853870 is 78358518612.

216815853870 is a `hidden beast` number, since 21 + 6 + 8 + 1 + 585 + 38 + 7 + 0 = 666.

It is a super-2 number, since 2×216815853870² (a number of 23 digits) contains 22 as substring.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216815853871) by changing a digit.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 2105008239 + ... + 2105008341.

It is an arithmetic number, because the mean of its divisors is an integer number (1011441600).

Almost surely, 2^216815853870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216815853870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (388393574400).

216815853870 is an abundant number, since it is smaller than the sum of its proper divisors (559971294930).

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

216815853870 is a wasteful number, since it uses less digits than its factorization.

216815853870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 3225600, while the sum is 54.

The spelling of 216815853870 in words is "two hundred sixteen billion, eight hundred fifteen million, eight hundred fifty-three thousand, eight hundred seventy".