20981736 has 48 divisors (see below), whose sum is σ = 57526560. Its totient is φ = 6907680.

The previous prime is 20981711. The next prime is 20981747. The reversal of 20981736 is 63718902.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20981736.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4221 + ... + 7731.

It is an arithmetic number, because the mean of its divisors is an integer number (1198470).

Almost surely, 2^20981736 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 20981736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28763280).

20981736 is an abundant number, since it is smaller than the sum of its proper divisors (36544824).

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

20981736 is a wasteful number, since it uses less digits than its factorization.

20981736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3606 (or 3599 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 20981736 is about 4580.5824957095. The cubic root of 20981736 is about 275.8124119139.

The spelling of 20981736 in words is "twenty million, nine hundred eighty-one thousand, seven hundred thirty-six".