20689091 has 2 divisors, whose sum is σ = 20689092. Its totient is φ = 20689090.

The previous prime is 20689087. The next prime is 20689099. The reversal of 20689091 is 19098602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20689091 - 2² = 20689087 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20689099) 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 as a sum of consecutive naturals, namely, 10344545 + 10344546.

It is an arithmetic number, because the mean of its divisors is an integer number (10344546).

Almost surely, 2^20689091 is an apocalyptic number.

20689091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20689091 is an equidigital number, since it uses as much as digits as its factorization.

20689091 is an odious number, because the sum of its binary digits is odd.

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

The square root of 20689091 is about 4548.5262448402. The cubic root of 20689091 is about 274.5240959026.

The spelling of 20689091 in words is "twenty million, six hundred eighty-nine thousand, ninety-one".