20665555 has 8 divisors (see below), whose sum is σ = 24966000. Its totient is φ = 16420896.

The previous prime is 20665549. The next prime is 20665577. The reversal of 20665555 is 55556602.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20665555 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20665555.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13125 + ... + 14614.

It is an arithmetic number, because the mean of its divisors is an integer number (3120750).

Almost surely, 2^20665555 is an apocalyptic number.

20665555 is a deficient number, since it is larger than the sum of its proper divisors (4300445).

20665555 is a wasteful number, since it uses less digits than its factorization.

20665555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27893.

The product of its (nonzero) digits is 45000, while the sum is 34.

The square root of 20665555 is about 4545.9382969856. The cubic root of 20665555 is about 274.4199564672.

The spelling of 20665555 in words is "twenty million, six hundred sixty-five thousand, five hundred fifty-five".