20691089 has 4 divisors (see below), whose sum is σ = 20712960. Its totient is φ = 20669220.

The previous prime is 20691079. The next prime is 20691109. The reversal of 20691089 is 98019602.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20691089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20691059) 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, 9449 + ... + 11430.

It is an arithmetic number, because the mean of its divisors is an integer number (5178240).

Almost surely, 2^20691089 is an apocalyptic number.

It is an amenable number.

20691089 is a deficient number, since it is larger than the sum of its proper divisors (21871).

20691089 is an equidigital number, since it uses as much as digits as its factorization.

20691089 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21870.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 20691089 is about 4548.7458711166. The cubic root of 20691089 is about 274.5329327897.

The spelling of 20691089 in words is "twenty million, six hundred ninety-one thousand, eighty-nine".