20998567 has 4 divisors (see below), whose sum is σ = 21120120. Its totient is φ = 20877016.

The previous prime is 20998531. The next prime is 20998583. The reversal of 20998567 is 76589902.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20998567 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20998267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60517 + ... + 60862.

It is an arithmetic number, because the mean of its divisors is an integer number (5280030).

Almost surely, 2^20998567 is an apocalyptic number.

20998567 is a deficient number, since it is larger than the sum of its proper divisors (121553).

20998567 is a wasteful number, since it uses less digits than its factorization.

20998567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121552.

The product of its (nonzero) digits is 272160, while the sum is 46.

The square root of 20998567 is about 4582.4193391701. The cubic root of 20998567 is about 275.8861420377.

The spelling of 20998567 in words is "twenty million, nine hundred ninety-eight thousand, five hundred sixty-seven".