20431978 has 8 divisors (see below), whose sum is σ = 35026272. Its totient is φ = 8756556.

The previous prime is 20431967. The next prime is 20431987. The reversal of 20431978 is 87913402.

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, 729700 + ... + 729727.

It is an arithmetic number, because the mean of its divisors is an integer number (4378284).

Almost surely, 2^20431978 is an apocalyptic number.

20431978 is a deficient number, since it is larger than the sum of its proper divisors (14594294).

20431978 is a wasteful number, since it uses less digits than its factorization.

20431978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1459436.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 20431978 is about 4520.1745541516. The cubic root of 20431978 is about 273.3821391465.

The spelling of 20431978 in words is "twenty million, four hundred thirty-one thousand, nine hundred seventy-eight".