20687169 has 16 divisors (see below), whose sum is σ = 28111104. Its totient is φ = 13530000.

The previous prime is 20687159. The next prime is 20687197. The reversal of 20687169 is 96178602.

It is a de Polignac number, because none of the positive numbers 2^k-20687169 is a prime.

It is a super-2 number, since 2×20687169² = 855917922469122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20687129) 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, 62334 + ... + 62664.

It is an arithmetic number, because the mean of its divisors is an integer number (1756944).

Almost surely, 2^20687169 is an apocalyptic number.

It is an amenable number.

20687169 is a deficient number, since it is larger than the sum of its proper divisors (7423935).

20687169 is a wasteful number, since it uses less digits than its factorization.

20687169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 668.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 20687169 is about 4548.3149627087. The cubic root of 20687169 is about 274.5155946164.

The spelling of 20687169 in words is "twenty million, six hundred eighty-seven thousand, one hundred sixty-nine".