20171978 has 8 divisors (see below), whose sum is σ = 30354372. Its totient is φ = 10053856.

The previous prime is 20171953. The next prime is 20171981. The reversal of 20171978 is 87917102.

It can be written as a sum of positive squares in 2 ways, for example, as 20133169 + 38809 = 4487^2 + 197^2 .

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

It is an unprimeable number.

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, 15275 + ... + 16542.

Almost surely, 2^20171978 is an apocalyptic number.

20171978 is a deficient number, since it is larger than the sum of its proper divisors (10182394).

20171978 is a wasteful number, since it uses less digits than its factorization.

20171978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32136.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20171978 is about 4491.3225223758. The cubic root of 20171978 is about 272.2175756962.

The spelling of 20171978 in words is "twenty million, one hundred seventy-one thousand, nine hundred seventy-eight".