20878217 has 4 divisors (see below), whose sum is σ = 21028560. Its totient is φ = 20727876.

The previous prime is 20878213. The next prime is 20878241. The reversal of 20878217 is 71287802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20878217 - 2² = 20878213 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20878211) 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 3 ways as a sum of consecutive naturals, for example, 74963 + ... + 75240.

It is an arithmetic number, because the mean of its divisors is an integer number (5257140).

Almost surely, 2^20878217 is an apocalyptic number.

It is an amenable number.

20878217 is a deficient number, since it is larger than the sum of its proper divisors (150343).

20878217 is a wasteful number, since it uses less digits than its factorization.

20878217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150342.

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 20878217 is about 4569.2687598783. The cubic root of 20878217 is about 275.3580658068.

The spelling of 20878217 in words is "twenty million, eight hundred seventy-eight thousand, two hundred seventeen".