20917985 has 8 divisors (see below), whose sum is σ = 27383616. Its totient is φ = 15213040.

The previous prime is 20917979. The next prime is 20917999. The reversal of 20917985 is 58971902.

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

It is not a de Polignac number, because 20917985 - 2⁴ = 20917969 is a prime.

It is a Duffinian number.

It is a Curzon number.

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, 190109 + ... + 190218.

It is an arithmetic number, because the mean of its divisors is an integer number (3422952).

Almost surely, 2^20917985 is an apocalyptic number.

It is an amenable number.

20917985 is a deficient number, since it is larger than the sum of its proper divisors (6465631).

20917985 is a wasteful number, since it uses less digits than its factorization.

20917985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 380343.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 20917985 is about 4573.6183706120. The cubic root of 20917985 is about 275.5327852964.

The spelling of 20917985 in words is "twenty million, nine hundred seventeen thousand, nine hundred eighty-five".