211810661172 has 54 divisors (see below), whose sum is σ = 588508834914. Its totient is φ = 64185047520.

The previous prime is 211810661171. The next prime is 211810661177. The reversal of 211810661172 is 271166018112.

211810661172 is a `hidden beast` number, since 21 + 1 + 8 + 10 + 6 + 611 + 7 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 126363186576 + 85447474596 = 355476^2 + 292314^2 .

It is a super-2 number, since 2×211810661172² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211810661171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 24308163 + ... + 24316874.

Almost surely, 2^211810661172 is an apocalyptic number.

211810661172 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

211810661172 is an abundant number, since it is smaller than the sum of its proper divisors (376698173742).

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

211810661172 is a wasteful number, since it uses less digits than its factorization.

211810661172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48625069 (or 48625053 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

Adding to 211810661172 its reverse (271166018112), we get a palindrome (482976679284).

The spelling of 211810661172 in words is "two hundred eleven billion, eight hundred ten million, six hundred sixty-one thousand, one hundred seventy-two".