20505688 has 16 divisors (see below), whose sum is σ = 43940880. Its totient is φ = 8788128.

The previous prime is 20505679. The next prime is 20505691. The reversal of 20505688 is 88650502.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 183031 + ... + 183142.

It is an arithmetic number, because the mean of its divisors is an integer number (2746305).

Almost surely, 2^20505688 is an apocalyptic number.

20505688 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

20505688 is an abundant number, since it is smaller than the sum of its proper divisors (23435192).

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

20505688 is a wasteful number, since it uses less digits than its factorization.

20505688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 366186 (or 366182 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 34.

The square root of 20505688 is about 4528.3206600240. The cubic root of 20505688 is about 273.7104939411.

The spelling of 20505688 in words is "twenty million, five hundred five thousand, six hundred eighty-eight".