211688987669 has 4 divisors (see below), whose sum is σ = 212785821996. Its totient is φ = 210592153344.

The previous prime is 211688987641. The next prime is 211688987717. The reversal of 211688987669 is 966789886112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50115538225 + 161573449444 = 223865^2 + 401962^2 .

It is a cyclic number.

It is not a de Polignac number, because 211688987669 - 2⁸ = 211688987413 is a prime.

It is a super-2 number, since 2×211688987669² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211688987269) 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 3 ways as a sum of consecutive naturals, for example, 548416874 + ... + 548417259.

It is an arithmetic number, because the mean of its divisors is an integer number (53196455499).

Almost surely, 2^211688987669 is an apocalyptic number.

It is an amenable number.

211688987669 is a deficient number, since it is larger than the sum of its proper divisors (1096834327).

211688987669 is a wasteful number, since it uses less digits than its factorization.

211688987669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1096834326.

The product of its digits is 125411328, while the sum is 71.

The spelling of 211688987669 in words is "two hundred eleven billion, six hundred eighty-eight million, nine hundred eighty-seven thousand, six hundred sixty-nine".