20988978 has 32 divisors (see below), whose sum is σ = 43186176. Its totient is φ = 6797328.

The previous prime is 20988973. The next prime is 20988991. The reversal of 20988978 is 87988902.

It is a self number, because there is not a number n which added to its sum of digits gives 20988978.

It is not an unprimeable number, because it can be changed into a prime (20988973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74025 + ... + 74307.

It is an arithmetic number, because the mean of its divisors is an integer number (1349568).

Almost surely, 2^20988978 is an apocalyptic number.

20988978 is an abundant number, since it is smaller than the sum of its proper divisors (22197198).

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

20988978 is a wasteful number, since it uses less digits than its factorization.

20988978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 598.

The product of its (nonzero) digits is 580608, while the sum is 51.

The square root of 20988978 is about 4581.3729383232. The cubic root of 20988978 is about 275.8441411557.

The spelling of 20988978 in words is "twenty million, nine hundred eighty-eight thousand, nine hundred seventy-eight".