21166062221561 has 8 divisors (see below), whose sum is σ = 22281256108800. Its totient is φ = 20050987395600.

The previous prime is 21166062221539. The next prime is 21166062221609. The reversal of 21166062221561 is 16512226066112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21166062221561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21166062221261) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 29400290 + ... + 30111611.

It is an arithmetic number, because the mean of its divisors is an integer number (2785157013600).

Almost surely, 2^{21166062221561} is an apocalyptic number.

It is an amenable number.

21166062221561 is a deficient number, since it is larger than the sum of its proper divisors (1115193887239).

21166062221561 is a wasteful number, since it uses less digits than its factorization.

21166062221561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59530639.

The product of its (nonzero) digits is 103680, while the sum is 41.

Adding to 21166062221561 its reverse (16512226066112), we get a palindrome (37678288287673).

The spelling of 21166062221561 in words is "twenty-one trillion, one hundred sixty-six billion, sixty-two million, two hundred twenty-one thousand, five hundred sixty-one".