20839987 has 8 divisors (see below), whose sum is σ = 23868000. Its totient is φ = 17824704.

The previous prime is 20839969. The next prime is 20839997. The reversal of 20839987 is 78993802.

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 20839987 - 2¹⁵ = 20807219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20839927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 639 + ... + 6487.

It is an arithmetic number, because the mean of its divisors is an integer number (2983500).

Almost surely, 2^20839987 is an apocalyptic number.

20839987 is a deficient number, since it is larger than the sum of its proper divisors (3028013).

20839987 is an equidigital number, since it uses as much as digits as its factorization.

20839987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6365.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 20839987 is about 4565.0834603543. The cubic root of 20839987 is about 275.1898941876.

The spelling of 20839987 in words is "twenty million, eight hundred thirty-nine thousand, nine hundred eighty-seven".