20688305 has 16 divisors (see below), whose sum is σ = 27172800. Its totient is φ = 14996160.

The previous prime is 20688301. The next prime is 20688329. The reversal of 20688305 is 50388602.

It is not a de Polignac number, because 20688305 - 2² = 20688301 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20688301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27626 + ... + 28364.

It is an arithmetic number, because the mean of its divisors is an integer number (1698300).

Almost surely, 2^20688305 is an apocalyptic number.

It is an amenable number.

20688305 is a deficient number, since it is larger than the sum of its proper divisors (6484495).

20688305 is a wasteful number, since it uses less digits than its factorization.

20688305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1264.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 20688305 is about 4548.4398424075. The cubic root of 20688305 is about 274.5206193736.

The spelling of 20688305 in words is "twenty million, six hundred eighty-eight thousand, three hundred five".