20997497 has 4 divisors (see below), whose sum is σ = 21126480. Its totient is φ = 20868516.

The previous prime is 20997491. The next prime is 20997511. The reversal of 20997497 is 79479902.

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 not a de Polignac number, because 20997497 - 2¹⁰ = 20996473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20997491) 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, 64247 + ... + 64572.

It is an arithmetic number, because the mean of its divisors is an integer number (5281620).

Almost surely, 2^20997497 is an apocalyptic number.

It is an amenable number.

20997497 is a deficient number, since it is larger than the sum of its proper divisors (128983).

20997497 is a wasteful number, since it uses less digits than its factorization.

20997497 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128982.

The product of its (nonzero) digits is 285768, while the sum is 47.

The square root of 20997497 is about 4582.3025871280. The cubic root of 20997497 is about 275.8814559530.

The spelling of 20997497 in words is "twenty million, nine hundred ninety-seven thousand, four hundred ninety-seven".