20878665 has 16 divisors (see below), whose sum is σ = 33520128. Its totient is φ = 11097216.

The previous prime is 20878631. The next prime is 20878667. The reversal of 20878665 is 56687802.

It is not a de Polignac number, because 20878665 - 2⁷ = 20878537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20878667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2472 + ... + 6918.

It is an arithmetic number, because the mean of its divisors is an integer number (2095008).

Almost surely, 2^20878665 is an apocalyptic number.

It is an amenable number.

20878665 is a deficient number, since it is larger than the sum of its proper divisors (12641463).

20878665 is a wasteful number, since it uses less digits than its factorization.

20878665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4768.

The product of its (nonzero) digits is 161280, while the sum is 42.

The square root of 20878665 is about 4569.3177827768. The cubic root of 20878665 is about 275.3600353161.

The spelling of 20878665 in words is "twenty million, eight hundred seventy-eight thousand, six hundred sixty-five".