20520397 has 4 divisors (see below), whose sum is σ = 20530300. Its totient is φ = 20510496.

The previous prime is 20520389. The next prime is 20520403. The reversal of 20520397 is 79302502.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 79302502 = 2 ⋅39651251.

It can be written as a sum of positive squares in 2 ways, for example, as 17355556 + 3164841 = 4166^2 + 1779^2 .

It is a cyclic number.

It is not a de Polignac number, because 20520397 - 2³ = 20520389 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 (20520307) 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, 522 + ... + 6427.

It is an arithmetic number, because the mean of its divisors is an integer number (5132575).

Almost surely, 2^20520397 is an apocalyptic number.

It is an amenable number.

20520397 is a deficient number, since it is larger than the sum of its proper divisors (9903).

20520397 is an equidigital number, since it uses as much as digits as its factorization.

20520397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9902.

The product of its (nonzero) digits is 3780, while the sum is 28.

The square root of 20520397 is about 4529.9444808960. The cubic root of 20520397 is about 273.7759236794.

Adding to 20520397 its reverse (79302502), we get a palindrome (99822899).

It can be divided in two parts, 205 and 20397, that added together give a palindrome (20602).

The spelling of 20520397 in words is "twenty million, five hundred twenty thousand, three hundred ninety-seven".