20665657393 has 4 divisors (see below), whose sum is σ = 20666732580. Its totient is φ = 20664582208.

The previous prime is 20665657319. The next prime is 20665657427. The reversal of 20665657393 is 39375656602.

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 8026726464 + 12638930929 = 89592^2 + 112423^2 .

It is a cyclic number.

It is not a de Polignac number, because 20665657393 - 2⁹ = 20665656881 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20665657393.

It is not an unprimeable number, because it can be changed into a prime (20665657993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 508228 + ... + 547381.

It is an arithmetic number, because the mean of its divisors is an integer number (5166683145).

Almost surely, 2^20665657393 is an apocalyptic number.

It is an amenable number.

20665657393 is a deficient number, since it is larger than the sum of its proper divisors (1075187).

20665657393 is a wasteful number, since it uses less digits than its factorization.

20665657393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075186.

The product of its (nonzero) digits is 6123600, while the sum is 52.

The spelling of 20665657393 in words is "twenty billion, six hundred sixty-five million, six hundred fifty-seven thousand, three hundred ninety-three".