21666277761667 has 16 divisors (see below), whose sum is σ = 27012615858432. Its totient is φ = 16882742769120.

The previous prime is 21666277761617. The next prime is 21666277761749. The reversal of 21666277761667 is 76616777266612.

It is a cyclic number.

It is not a de Polignac number, because 21666277761667 - 2¹⁵ = 21666277728899 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21666277761596 and 21666277761605.

It is not an unprimeable number, because it can be changed into a prime (21666277761617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24892608 + ... + 25748290.

It is an arithmetic number, because the mean of its divisors is an integer number (1688288491152).

Almost surely, 2^{21666277761667} is an apocalyptic number.

21666277761667 is a deficient number, since it is larger than the sum of its proper divisors (5346338096765).

21666277761667 is a wasteful number, since it uses less digits than its factorization.

21666277761667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1184538.

The product of its digits is 448084224, while the sum is 70.

The spelling of 21666277761667 in words is "twenty-one trillion, six hundred sixty-six billion, two hundred seventy-seven million, seven hundred sixty-one thousand, six hundred sixty-seven".