20978944 has 72 divisors (see below), whose sum is σ = 50037120. Its totient is φ = 8583168.

The previous prime is 20978941. The next prime is 20978981. The reversal of 20978944 is 44987902.

It is a self number, because there is not a number n which added to its sum of digits gives 20978944.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20978941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40962 + ... + 41470.

It is an arithmetic number, because the mean of its divisors is an integer number (694960).

Almost surely, 2^20978944 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20978944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25018560).

20978944 is an abundant number, since it is smaller than the sum of its proper divisors (29058176).

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

20978944 is an equidigital number, since it uses as much as digits as its factorization.

20978944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 20978944 is about 4580.2777208375. The cubic root of 20978944 is about 275.8001774256.

The spelling of 20978944 in words is "twenty million, nine hundred seventy-eight thousand, nine hundred forty-four".