20816388 has 54 divisors (see below), whose sum is σ = 53946074. Its totient is φ = 6766848.

The previous prime is 20816387. The next prime is 20816413. The reversal of 20816388 is 88361802.

It can be written as a sum of positive squares in 3 ways, for example, as 186624 + 20629764 = 432^2 + 4542^2 .

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

It is not an unprimeable number, because it can be changed into a prime (20816387) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 233848 + ... + 233936.

Almost surely, 2^20816388 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 20816388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26973037).

20816388 is an abundant number, since it is smaller than the sum of its proper divisors (33129686).

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

20816388 is a wasteful number, since it uses less digits than its factorization.

20816388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 20816388 is about 4562.4979999996. The cubic root of 20816388 is about 275.0859808281.

The spelling of 20816388 in words is "twenty million, eight hundred sixteen thousand, three hundred eighty-eight".