20680985 has 16 divisors (see below), whose sum is σ = 26829264. Its totient is φ = 15213312.

The previous prime is 20680981. The next prime is 20680997. The reversal of 20680985 is 58908602.

It can be written as a sum of positive squares in 8 ways, for example, as 5031049 + 15649936 = 2243^2 + 3956^2 .

It is a cyclic number.

It is not a de Polignac number, because 20680985 - 2² = 20680981 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20680981) 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, 23819 + ... + 24671.

It is an arithmetic number, because the mean of its divisors is an integer number (1676829).

Almost surely, 2^20680985 is an apocalyptic number.

It is an amenable number.

20680985 is a deficient number, since it is larger than the sum of its proper divisors (6148279).

20680985 is a wasteful number, since it uses less digits than its factorization.

20680985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244.

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

The square root of 20680985 is about 4547.6350996974. The cubic root of 20680985 is about 274.4882383097.

The spelling of 20680985 in words is "twenty million, six hundred eighty thousand, nine hundred eighty-five".