20912687 has 4 divisors (see below), whose sum is σ = 21307320. Its totient is φ = 20518056.

The previous prime is 20912677. The next prime is 20912707. The reversal of 20912687 is 78621902.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20912687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20912627) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 197237 + ... + 197342.

It is an arithmetic number, because the mean of its divisors is an integer number (5326830).

Almost surely, 2^20912687 is an apocalyptic number.

20912687 is a deficient number, since it is larger than the sum of its proper divisors (394633).

20912687 is an equidigital number, since it uses as much as digits as its factorization.

20912687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394632.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 20912687 is about 4573.0391426271. The cubic root of 20912687 is about 275.5095214885.

The spelling of 20912687 in words is "twenty million, nine hundred twelve thousand, six hundred eighty-seven".