20997493 has 12 divisors (see below), whose sum is σ = 23330860. Its totient is φ = 18881280.

The previous prime is 20997491. The next prime is 20997511. The reversal of 20997493 is 39479902.

It can be written as a sum of positive squares in 2 ways, for example, as 15507844 + 5489649 = 3938^2 + 2343^2 .

It is not a de Polignac number, because 20997493 - 2¹ = 20997491 is a prime.

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent 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 11 ways as a sum of consecutive naturals, for example, 10843 + ... + 12631.

Almost surely, 2^20997493 is an apocalyptic number.

It is an amenable number.

20997493 is a deficient number, since it is larger than the sum of its proper divisors (2333367).

20997493 is a wasteful number, since it uses less digits than its factorization.

20997493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1908 (or 1897 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 43.

The square root of 20997493 is about 4582.3021506662. The cubic root of 20997493 is about 275.8814384347.

The spelling of 20997493 in words is "twenty million, nine hundred ninety-seven thousand, four hundred ninety-three".