20523121 has 4 divisors (see below), whose sum is σ = 20544244. Its totient is φ = 20502000.

The previous prime is 20523119. The next prime is 20523127. The reversal of 20523121 is 12132502.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9394225 + 11128896 = 3065^2 + 3336^2 .

It is a cyclic number.

It is not a de Polignac number, because 20523121 - 2¹ = 20523119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20523095 and 20523104.

It is not an unprimeable number, because it can be changed into a prime (20523127) 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, 9030 + ... + 11071.

It is an arithmetic number, because the mean of its divisors is an integer number (5136061).

Almost surely, 2^20523121 is an apocalyptic number.

It is an amenable number.

20523121 is a deficient number, since it is larger than the sum of its proper divisors (21123).

20523121 is a wasteful number, since it uses less digits than its factorization.

20523121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21122.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 20523121 is about 4530.2451368552. The cubic root of 20523121 is about 273.7880373603.

Adding to 20523121 its reverse (12132502), we get a palindrome (32655623).

The spelling of 20523121 in words is "twenty million, five hundred twenty-three thousand, one hundred twenty-one".