20686989 has 4 divisors (see below), whose sum is σ = 27582656. Its totient is φ = 13791324.

The previous prime is 20686969. The next prime is 20687027. The reversal of 20686989 is 98968602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20686989 - 2⁸ = 20686733 is a prime.

It is a super-2 number, since 2×20686989² = 855903027772242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20686949) 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 3 ways as a sum of consecutive naturals, for example, 3447829 + ... + 3447834.

It is an arithmetic number, because the mean of its divisors is an integer number (6895664).

Almost surely, 2^20686989 is an apocalyptic number.

It is an amenable number.

20686989 is a deficient number, since it is larger than the sum of its proper divisors (6895667).

20686989 is an equidigital number, since it uses as much as digits as its factorization.

20686989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6895666.

The product of its (nonzero) digits is 373248, while the sum is 48.

The square root of 20686989 is about 4548.2951751178. The cubic root of 20686989 is about 274.5147984232.

The spelling of 20686989 in words is "twenty million, six hundred eighty-six thousand, nine hundred eighty-nine".