20978329 has 4 divisors (see below), whose sum is σ = 21062160. Its totient is φ = 20894500.

The previous prime is 20978317. The next prime is 20978359. The reversal of 20978329 is 92387902.

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 20978329 - 2⁷ = 20978201 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20978291 and 20978300.

It is not an unprimeable number, because it can be changed into a prime (20978359) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41539 + ... + 42040.

It is an arithmetic number, because the mean of its divisors is an integer number (5265540).

Almost surely, 2^20978329 is an apocalyptic number.

It is an amenable number.

20978329 is a deficient number, since it is larger than the sum of its proper divisors (83831).

20978329 is an equidigital number, since it uses as much as digits as its factorization.

20978329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83830.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 20978329 is about 4580.2105846784. The cubic root of 20978329 is about 275.7974823620.

The spelling of 20978329 in words is "twenty million, nine hundred seventy-eight thousand, three hundred twenty-nine".