21166615334491 has 16 divisors (see below), whose sum is σ = 23176304236800. Its totient is φ = 19171228146400.

The previous prime is 21166615334461. The next prime is 21166615334561. The reversal of 21166615334491 is 19443351666112.

It is not a de Polignac number, because 21166615334491 - 2¹³ = 21166615326299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21166615334411) 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, 5582820 + ... + 8573278.

It is an arithmetic number, because the mean of its divisors is an integer number (1448519014800).

Almost surely, 2^{21166615334491} is an apocalyptic number.

21166615334491 is a deficient number, since it is larger than the sum of its proper divisors (2009688902309).

21166615334491 is a wasteful number, since it uses less digits than its factorization.

21166615334491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2992850.

The product of its digits is 2799360, while the sum is 52.

The spelling of 21166615334491 in words is "twenty-one trillion, one hundred sixty-six billion, six hundred fifteen million, three hundred thirty-four thousand, four hundred ninety-one".