20391636 has 48 divisors (see below), whose sum is σ = 53040960. Its totient is φ = 6059520.

The previous prime is 20391599. The next prime is 20391647. The reversal of 20391636 is 63619302.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1246 + ... + 6506.

It is an arithmetic number, because the mean of its divisors is an integer number (1105020).

Almost surely, 2^20391636 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 20391636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26520480).

20391636 is an abundant number, since it is smaller than the sum of its proper divisors (32649324).

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

20391636 is a wasteful number, since it uses less digits than its factorization.

20391636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5304 (or 5302 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 20391636 is about 4515.7099109664. The cubic root of 20391636 is about 273.2020937811.

The spelling of 20391636 in words is "twenty million, three hundred ninety-one thousand, six hundred thirty-six".