211156661 has 8 divisors (see below), whose sum is σ = 214864920. Its totient is φ = 207470592.

The previous prime is 211156619. The next prime is 211156663. The reversal of 211156661 is 166651112.

It can be written as a sum of positive squares in 4 ways, for example, as 38365636 + 172791025 = 6194^2 + 13145^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 211156661 - 2¹⁸ = 210894517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211156663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14261 + ... + 25013.

It is an arithmetic number, because the mean of its divisors is an integer number (26858115).

Almost surely, 2^211156661 is an apocalyptic number.

It is an amenable number.

211156661 is a deficient number, since it is larger than the sum of its proper divisors (3708259).

211156661 is a wasteful number, since it uses less digits than its factorization.

211156661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11095.

The product of its digits is 2160, while the sum is 29.

The square root of 211156661 is about 14531.2305397719. The cubic root of 211156661 is about 595.4814839607.

The spelling of 211156661 in words is "two hundred eleven million, one hundred fifty-six thousand, six hundred sixty-one".