21661013873 has 16 divisors (see below), whose sum is σ = 22538219520. Its totient is φ = 20795346000.

The previous prime is 21661013867. The next prime is 21661013977. The reversal of 21661013873 is 37831016612.

It is a cyclic number.

It is not a de Polignac number, because 21661013873 - 2⁶ = 21661013809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21661013833) 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 15 ways as a sum of consecutive naturals, for example, 4018286 + ... + 4023672.

It is an arithmetic number, because the mean of its divisors is an integer number (1408638720).

Almost surely, 2^21661013873 is an apocalyptic number.

It is an amenable number.

21661013873 is a deficient number, since it is larger than the sum of its proper divisors (877205647).

21661013873 is a wasteful number, since it uses less digits than its factorization.

21661013873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6428.

The product of its (nonzero) digits is 36288, while the sum is 38.

The spelling of 21661013873 in words is "twenty-one billion, six hundred sixty-one million, thirteen thousand, eight hundred seventy-three".