20781888 has 56 divisors (see below), whose sum is σ = 58228992. Its totient is φ = 6518784.

The previous prime is 20781863. The next prime is 20781889. The reversal of 20781888 is 88818702.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20781889) 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 7 ways as a sum of consecutive naturals, for example, 81 + ... + 6447.

Almost surely, 2^20781888 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 20781888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29114496).

20781888 is an abundant number, since it is smaller than the sum of its proper divisors (37447104).

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

20781888 is a wasteful number, since it uses less digits than its factorization.

20781888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6399 (or 6389 counting only the distinct ones).

The product of its (nonzero) digits is 57344, while the sum is 42.

The square root of 20781888 is about 4558.7156085898. The cubic root of 20781888 is about 274.9339257234.

The spelling of 20781888 in words is "twenty million, seven hundred eighty-one thousand, eight hundred eighty-eight".