211581017856 has 432 divisors, whose sum is σ = 684479839680. Its totient is φ = 62426972160.

The previous prime is 211581017839. The next prime is 211581017867. The reversal of 211581017856 is 658710185112.

211581017856 is a `hidden beast` number, since 2 + 1 + 1 + 581 + 0 + 17 + 8 + 56 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 78682560 + ... + 78685248.

Almost surely, 2^211581017856 is an apocalyptic number.

211581017856 is a gapful number since it is divisible by the number (26) 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 211581017856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (342239919840).

211581017856 is an abundant number, since it is smaller than the sum of its proper divisors (472898821824).

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

211581017856 is a wasteful number, since it uses less digits than its factorization.

211581017856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2832 (or 2815 counting only the distinct ones).

The product of its (nonzero) digits is 134400, while the sum is 45.

The spelling of 211581017856 in words is "two hundred eleven billion, five hundred eighty-one million, seventeen thousand, eight hundred fifty-six".