20685281 has 8 divisors (see below), whose sum is σ = 22051200. Its totient is φ = 19347120.

The previous prime is 20685239. The next prime is 20685307. The reversal of 20685281 is 18258602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20685281 is a prime.

It is a super-2 number, since 2×20685281² = 855761700097922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20682281) 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 in 7 ways as a sum of consecutive naturals, for example, 5390 + ... + 8391.

It is an arithmetic number, because the mean of its divisors is an integer number (2756400).

Almost surely, 2^20685281 is an apocalyptic number.

It is an amenable number.

20685281 is a deficient number, since it is larger than the sum of its proper divisors (1365919).

20685281 is a wasteful number, since it uses less digits than its factorization.

20685281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13879.

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 20685281 is about 4548.1074085822. The cubic root of 20685281 is about 274.5072432044.

The spelling of 20685281 in words is "twenty million, six hundred eighty-five thousand, two hundred eighty-one".