20915984 has 40 divisors (see below), whose sum is σ = 43309728. Its totient is φ = 9751040.

The previous prime is 20915981. The next prime is 20916019. The reversal of 20915984 is 48951902.

It is not an unprimeable number, because it can be changed into a prime (20915981) 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, 35339 + ... + 35925.

Almost surely, 2^20915984 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 20915984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21654864).

20915984 is an abundant number, since it is smaller than the sum of its proper divisors (22393744).

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

20915984 is a wasteful number, since it uses less digits than its factorization.

20915984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 737 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 20915984 is about 4573.3996107928. The cubic root of 20915984 is about 275.5239992576.

The spelling of 20915984 in words is "twenty million, nine hundred fifteen thousand, nine hundred eighty-four".