20281808 has 10 divisors (see below), whose sum is σ = 39296034. Its totient is φ = 10140896.

The previous prime is 20281801. The next prime is 20281819. The reversal of 20281808 is 80818202.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 283024 = 4472^2 + 532^2 .

It is a super-2 number, since 2×20281808² = 822703471497728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20281801) 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 as a sum of consecutive naturals, namely, 633791 + ... + 633822.

Almost surely, 2^20281808 is an apocalyptic number.

It is an amenable number.

20281808 is a deficient number, since it is larger than the sum of its proper divisors (19014226).

20281808 is a wasteful number, since it uses less digits than its factorization.

20281808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1267621 (or 1267615 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 29.

The square root of 20281808 is about 4503.5328354526. The cubic root of 20281808 is about 272.7107277775.

The spelling of 20281808 in words is "twenty million, two hundred eighty-one thousand, eight hundred eight".