21666676666665 has 32 divisors (see below), whose sum is σ = 35245440147456. Its totient is φ = 11362754108160.

The previous prime is 21666676666597. The next prime is 21666676666681. The reversal of 21666676666665 is 56666667666612.

It is not a de Polignac number, because 21666676666665 - 2¹⁸ = 21666676404521 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 423849 + ... + 6596438.

It is an arithmetic number, because the mean of its divisors is an integer number (1101420004608).

Almost surely, 2^{21666676666665} is an apocalyptic number.

It is an amenable number.

21666676666665 is a deficient number, since it is larger than the sum of its proper divisors (13578763480791).

21666676666665 is a wasteful number, since it uses less digits than its factorization.

21666676666665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7023729.

The product of its digits is 4232632320, while the sum is 75.

The spelling of 21666676666665 in words is "twenty-one trillion, six hundred sixty-six billion, six hundred seventy-six million, six hundred sixty-six thousand, six hundred sixty-five".