20840687 has 8 divisors (see below), whose sum is σ = 23990400. Its totient is φ = 17734104.

The previous prime is 20840683. The next prime is 20840707. The reversal of 20840687 is 78604802.

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

It is a cyclic number.

It is not a de Polignac number, because 20840687 - 2² = 20840683 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840683) 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, 9737 + ... + 11682.

It is an arithmetic number, because the mean of its divisors is an integer number (2998800).

Almost surely, 2^20840687 is an apocalyptic number.

20840687 is a deficient number, since it is larger than the sum of its proper divisors (3149713).

20840687 is a wasteful number, since it uses less digits than its factorization.

20840687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21565.

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 20840687 is about 4565.1601286264. The cubic root of 20840687 is about 275.1929752959.

The spelling of 20840687 in words is "twenty million, eight hundred forty thousand, six hundred eighty-seven".