20747808 has 72 divisors (see below), whose sum is σ = 60019596. Its totient is φ = 6796800.

The previous prime is 20747777. The next prime is 20747809. The reversal of 20747808 is 80874702.

It can be written as a sum of positive squares in 2 ways, for example, as 20684304 + 63504 = 4548^2 + 252^2 .

It is a tau number, because it is divible by the number of its divisors (72).

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 (20747809) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16978 + ... + 18158.

Almost surely, 2^20747808 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 20747808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30009798).

20747808 is an abundant number, since it is smaller than the sum of its proper divisors (39271788).

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

20747808 is a wasteful number, since it uses less digits than its factorization.

20747808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258 (or 1247 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The square root of 20747808 is about 4554.9761799597. The cubic root of 20747808 is about 274.7835564107.

The spelling of 20747808 in words is "twenty million, seven hundred forty-seven thousand, eight hundred eight".