20979984 has 20 divisors (see below), whose sum is σ = 54198416. Its totient is φ = 6993312.

The previous prime is 20979983. The next prime is 20980027. The reversal of 20979984 is 48997902.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48), and also a Moran number because the ratio is a prime number: 437083 = 20979984 / (2 + 0 + 9 + 7 + 9 + 9 + 8 + 4).

It is not an unprimeable number, because it can be changed into a prime (20979983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 218494 + ... + 218589.

Almost surely, 2^20979984 is an apocalyptic number.

20979984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20979984 is an abundant number, since it is smaller than the sum of its proper divisors (33218432).

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

20979984 is a wasteful number, since it uses less digits than its factorization.

20979984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 437094 (or 437088 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 48.

The square root of 20979984 is about 4580.3912496642. The cubic root of 20979984 is about 275.8047348117.

The spelling of 20979984 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred eighty-four".