20681687 has 8 divisors (see below), whose sum is σ = 22390704. Its totient is φ = 18989568.

The previous prime is 20681663. The next prime is 20681701. The reversal of 20681687 is 78618602.

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

It is not a de Polignac number, because 20681687 - 2¹⁸ = 20419543 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20681687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20611687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1613 + ... + 6630.

It is an arithmetic number, because the mean of its divisors is an integer number (2798838).

Almost surely, 2^20681687 is an apocalyptic number.

20681687 is a deficient number, since it is larger than the sum of its proper divisors (1709017).

20681687 is a wasteful number, since it uses less digits than its factorization.

20681687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8449.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20681687 is about 4547.7122820161. The cubic root of 20681687 is about 274.4913440380.

The spelling of 20681687 in words is "twenty million, six hundred eighty-one thousand, six hundred eighty-seven".