2121403653666 has 48 divisors (see below), whose sum is σ = 5017347811008. Its totient is φ = 642449464800.

The previous prime is 2121403653659. The next prime is 2121403653703. The reversal of 2121403653666 is 6663563041212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3015405 + ... + 3651776.

It is an arithmetic number, because the mean of its divisors is an integer number (104528079396).

Almost surely, 2^{2121403653666} is an apocalyptic number.

2121403653666 is an abundant number, since it is smaller than the sum of its proper divisors (2895944157342).

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

2121403653666 is a wasteful number, since it uses less digits than its factorization.

2121403653666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6668807 (or 6668804 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 45.

Adding to 2121403653666 its reverse (6663563041212), we get a palindrome (8784966694878).

The spelling of 2121403653666 in words is "two trillion, one hundred twenty-one billion, four hundred three million, six hundred fifty-three thousand, six hundred sixty-six".