20942666665 has 4 divisors (see below), whose sum is σ = 25131200004. Its totient is φ = 16754133328.

The previous prime is 20942666663. The next prime is 20942666687. The reversal of 20942666665 is 56666624902.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5749885584 + 15192781081 = 75828^2 + 123259^2 .

It is a cyclic number.

It is not a de Polignac number, because 20942666665 - 2¹ = 20942666663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20942666663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2094266662 + ... + 2094266671.

It is an arithmetic number, because the mean of its divisors is an integer number (6282800001).

Almost surely, 2^20942666665 is an apocalyptic number.

It is an amenable number.

20942666665 is a deficient number, since it is larger than the sum of its proper divisors (4188533339).

20942666665 is an equidigital number, since it uses as much as digits as its factorization.

20942666665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4188533338.

The product of its (nonzero) digits is 5598720, while the sum is 52.

The spelling of 20942666665 in words is "twenty billion, nine hundred forty-two million, six hundred sixty-six thousand, six hundred sixty-five".