20399808 has 112 divisors (see below), whose sum is σ = 63495936. Its totient is φ = 5698560.

The previous prime is 20399807. The next prime is 20399831. The reversal of 20399808 is 80899302.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (20399807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27085 + ... + 27827.

It is an arithmetic number, because the mean of its divisors is an integer number (566928).

Almost surely, 2^20399808 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 20399808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31747968).

20399808 is an abundant number, since it is smaller than the sum of its proper divisors (43096128).

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

20399808 is a wasteful number, since it uses less digits than its factorization.

20399808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 782 (or 772 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 20399808 is about 4516.6146614472. The cubic root of 20399808 is about 273.2385843850.

The spelling of 20399808 in words is "twenty million, three hundred ninety-nine thousand, eight hundred eight".