20685890 has 8 divisors (see below), whose sum is σ = 37234620. Its totient is φ = 8274352.

The previous prime is 20685883. The next prime is 20685919. The reversal of 20685890 is 9858602.

It can be written as a sum of positive squares in 2 ways, for example, as 20241001 + 444889 = 4499^2 + 667^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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, 1034285 + ... + 1034304.

Almost surely, 2^20685890 is an apocalyptic number.

20685890 is a deficient number, since it is larger than the sum of its proper divisors (16548730).

20685890 is a wasteful number, since it uses less digits than its factorization.

20685890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2068596.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 20685890 is about 4548.1743590148. The cubic root of 20685890 is about 274.5099371211.

The spelling of 20685890 in words is "twenty million, six hundred eighty-five thousand, eight hundred ninety".