211630661 has 16 divisors (see below), whose sum is σ = 241738560. Its totient is φ = 183496320.

The previous prime is 211630621. The next prime is 211630663. The reversal of 211630661 is 166036112.

211630661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211630661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 211630661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211630663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22481 + ... + 30473.

It is an arithmetic number, because the mean of its divisors is an integer number (15108660).

Almost surely, 2^211630661 is an apocalyptic number.

It is an amenable number.

211630661 is a deficient number, since it is larger than the sum of its proper divisors (30107899).

211630661 is a wasteful number, since it uses less digits than its factorization.

211630661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8116.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 211630661 is about 14547.5310963751. The cubic root of 211630661 is about 595.9267257109.

Adding to 211630661 its reverse (166036112), we get a palindrome (377666773).

The spelling of 211630661 in words is "two hundred eleven million, six hundred thirty thousand, six hundred sixty-one".