20978305 has 8 divisors (see below), whose sum is σ = 25204032. Its totient is φ = 16762608.

The previous prime is 20978273. The next prime is 20978311. The reversal of 20978305 is 50387902.

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

It is a cyclic number.

It is not a de Polignac number, because 20978305 - 2⁵ = 20978273 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3342 + ... + 7288.

It is an arithmetic number, because the mean of its divisors is an integer number (3150504).

Almost surely, 2^20978305 is an apocalyptic number.

It is an amenable number.

20978305 is a deficient number, since it is larger than the sum of its proper divisors (4225727).

20978305 is a wasteful number, since it uses less digits than its factorization.

20978305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5015.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 20978305 is about 4580.2079647108. The cubic root of 20978305 is about 275.7973771877.

The spelling of 20978305 in words is "twenty million, nine hundred seventy-eight thousand, three hundred five".