20913808 has 40 divisors (see below), whose sum is σ = 44782848. Its totient is φ = 9411072.

The previous prime is 20913803. The next prime is 20913811. The reversal of 20913808 is 80831902.

It is a self number, because there is not a number n which added to its sum of digits gives 20913808.

It is not an unprimeable number, because it can be changed into a prime (20913803) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 4585 + ... + 7927.

Almost surely, 2^20913808 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 20913808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22391424).

20913808 is an abundant number, since it is smaller than the sum of its proper divisors (23869040).

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

20913808 is a wasteful number, since it uses less digits than its factorization.

20913808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3391 (or 3385 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 20913808 is about 4573.1617071781. The cubic root of 20913808 is about 275.5144441885.

The spelling of 20913808 in words is "twenty million, nine hundred thirteen thousand, eight hundred eight".