21011668667 has 4 divisors (see below), whose sum is σ = 22921820376. Its totient is φ = 19101516960.

The previous prime is 21011668609. The next prime is 21011668693. The reversal of 21011668667 is 76686611012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21011668667 - 2⁸ = 21011668411 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011668697) 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 3 ways as a sum of consecutive naturals, for example, 955075838 + ... + 955075859.

It is an arithmetic number, because the mean of its divisors is an integer number (5730455094).

Almost surely, 2^21011668667 is an apocalyptic number.

21011668667 is a deficient number, since it is larger than the sum of its proper divisors (1910151709).

21011668667 is a wasteful number, since it uses less digits than its factorization.

21011668667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1910151708.

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 21011668667 in words is "twenty-one billion, eleven million, six hundred sixty-eight thousand, six hundred sixty-seven".