211681766520 has 384 divisors, whose sum is σ = 791649331200. Its totient is φ = 48053440512.

The previous prime is 211681766519. The next prime is 211681766567. The reversal of 211681766520 is 25667186112.

211681766520 is a `hidden beast` number, since 2 + 1 + 1 + 68 + 1 + 7 + 66 + 520 = 666.

211681766520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 457195809 + ... + 457196271.

It is an arithmetic number, because the mean of its divisors is an integer number (2061586800).

Almost surely, 2^211681766520 is an apocalyptic number.

211681766520 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 211681766520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (395824665600).

211681766520 is an abundant number, since it is smaller than the sum of its proper divisors (579967564680).

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

211681766520 is a wasteful number, since it uses less digits than its factorization.

211681766520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1339 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 211681766520 in words is "two hundred eleven billion, six hundred eighty-one million, seven hundred sixty-six thousand, five hundred twenty".