20978778 has 32 divisors (see below), whose sum is σ = 43929216. Its totient is φ = 6671808.

The previous prime is 20978773. The next prime is 20978791. The reversal of 20978778 is 87787902.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20978773) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10875 + ... + 12657.

It is an arithmetic number, because the mean of its divisors is an integer number (1372788).

Almost surely, 2^20978778 is an apocalyptic number.

20978778 is an abundant number, since it is smaller than the sum of its proper divisors (22950438).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20978778 is a wasteful number, since it uses less digits than its factorization.

20978778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1878.

The product of its (nonzero) digits is 395136, while the sum is 48.

The square root of 20978778 is about 4580.2595996297. The cubic root of 20978778 is about 275.7994499827.

It can be divided in two parts, 209 and 78778, that added together give a palindrome (78987).

The spelling of 20978778 in words is "twenty million, nine hundred seventy-eight thousand, seven hundred seventy-eight".