20523397 has 4 divisors (see below), whose sum is σ = 20596716. Its totient is φ = 20450080.

The previous prime is 20523379. The next prime is 20523407. The reversal of 20523397 is 79332502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79332502 = 2 ⋅39666251.

It can be written as a sum of positive squares in 2 ways, for example, as 17422276 + 3101121 = 4174^2 + 1761^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20523397 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20523317) 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, 36238 + ... + 36799.

It is an arithmetic number, because the mean of its divisors is an integer number (5149179).

Almost surely, 2^20523397 is an apocalyptic number.

It is an amenable number.

20523397 is a deficient number, since it is larger than the sum of its proper divisors (73319).

20523397 is an equidigital number, since it uses as much as digits as its factorization.

20523397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73318.

The product of its (nonzero) digits is 11340, while the sum is 31.

The square root of 20523397 is about 4530.2755986805. The cubic root of 20523397 is about 273.7892646778.

Adding to 20523397 its reverse (79332502), we get a palindrome (99855899).

The spelling of 20523397 in words is "twenty million, five hundred twenty-three thousand, three hundred ninety-seven".