21111461666 has 8 divisors (see below), whose sum is σ = 31798592364. Its totient is φ = 10511930880.

The previous prime is 21111461663. The next prime is 21111461671. The reversal of 21111461666 is 66616411112.

It can be written as a sum of positive squares in 2 ways, for example, as 21031090441 + 80371225 = 145021^2 + 8965^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21111461663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21899375 + ... + 21900338.

Almost surely, 2^21111461666 is an apocalyptic number.

21111461666 is a deficient number, since it is larger than the sum of its proper divisors (10687130698).

21111461666 is a wasteful number, since it uses less digits than its factorization.

21111461666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43799956.

The product of its digits is 10368, while the sum is 35.

Adding to 21111461666 its reverse (66616411112), we get a palindrome (87727872778).

The spelling of 21111461666 in words is "twenty-one billion, one hundred eleven million, four hundred sixty-one thousand, six hundred sixty-six".