20987136 has 54 divisors (see below), whose sum is σ = 60517730. Its totient is φ = 6994944.

The previous prime is 20987119. The next prime is 20987143. The reversal of 20987136 is 63178902.

It can be written as a sum of positive squares in only one way, i.e., 14017536 + 6969600 = 3744^2 + 2640^2 .

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 20987136.

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 2251 + ... + 6858.

Almost surely, 2^20987136 is an apocalyptic number.

It is an amenable number.

20987136 is an abundant number, since it is smaller than the sum of its proper divisors (39530594).

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

20987136 is an equidigital number, since it uses as much as digits as its factorization.

20987136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9131 (or 9114 counting only the distinct ones).

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

The square root of 20987136 is about 4581.1719024721. The cubic root of 20987136 is about 275.8360715271.

The spelling of 20987136 in words is "twenty million, nine hundred eighty-seven thousand, one hundred thirty-six".