20998697 has 4 divisors (see below), whose sum is σ = 21722820. Its totient is φ = 20274576.

The previous prime is 20998673. The next prime is 20998727. The reversal of 20998697 is 79689902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15713296 + 5285401 = 3964^2 + 2299^2 .

It is a cyclic number.

It is not a de Polignac number, because 20998697 - 2⁶ = 20998633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20998297) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 362018 + ... + 362075.

It is an arithmetic number, because the mean of its divisors is an integer number (5430705).

Almost surely, 2^20998697 is an apocalyptic number.

It is an amenable number.

20998697 is a deficient number, since it is larger than the sum of its proper divisors (724123).

20998697 is an equidigital number, since it uses as much as digits as its factorization.

20998697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724122.

The product of its (nonzero) digits is 489888, while the sum is 50.

The square root of 20998697 is about 4582.4335237950. The cubic root of 20998697 is about 275.8867113642.

The spelling of 20998697 in words is "twenty million, nine hundred ninety-eight thousand, six hundred ninety-seven".