20998687 has 8 divisors (see below), whose sum is σ = 21739520. Its totient is φ = 20261880.

The previous prime is 20998673. The next prime is 20998727. The reversal of 20998687 is 78689902.

It is a happy number.

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 20998687 - 2²³ = 12610079 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 20998687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20998387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12838 + ... + 14380.

It is an arithmetic number, because the mean of its divisors is an integer number (2717440).

Almost surely, 2^20998687 is an apocalyptic number.

20998687 is a deficient number, since it is larger than the sum of its proper divisors (740833).

20998687 is a wasteful number, since it uses less digits than its factorization.

20998687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2013.

The product of its (nonzero) digits is 435456, while the sum is 49.

The square root of 20998687 is about 4582.4324326715. The cubic root of 20998687 is about 275.8866675699.

The spelling of 20998687 in words is "twenty million, nine hundred ninety-eight thousand, six hundred eighty-seven".