20642687 has 4 divisors (see below), whose sum is σ = 22230600. Its totient is φ = 19054776.

The previous prime is 20642659. The next prime is 20642689. The reversal of 20642687 is 78624602.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20642687 - 2¹⁴ = 20626303 is a prime.

It is a super-2 number, since 2×20642687² = 852241053159938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20642689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 793937 + ... + 793962.

It is an arithmetic number, because the mean of its divisors is an integer number (5557650).

Almost surely, 2^20642687 is an apocalyptic number.

20642687 is a deficient number, since it is larger than the sum of its proper divisors (1587913).

20642687 is a wasteful number, since it uses less digits than its factorization.

20642687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1587912.

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 20642687 is about 4543.4223884644. The cubic root of 20642687 is about 274.3186969601.

The spelling of 20642687 in words is "twenty million, six hundred forty-two thousand, six hundred eighty-seven".