20531523 has 4 divisors (see below), whose sum is σ = 27375368. Its totient is φ = 13687680.

The previous prime is 20531521. The next prime is 20531543. The reversal of 20531523 is 32513502.

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

It is not a de Polignac number, because 20531523 - 2¹ = 20531521 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20531523.

It is not an unprimeable number, because it can be changed into a prime (20531521) 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, 3421918 + ... + 3421923.

It is an arithmetic number, because the mean of its divisors is an integer number (6843842).

Almost surely, 2^20531523 is an apocalyptic number.

20531523 is a deficient number, since it is larger than the sum of its proper divisors (6843845).

20531523 is an equidigital number, since it uses as much as digits as its factorization.

20531523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6843844.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 20531523 is about 4531.1723648522. The cubic root of 20531523 is about 273.8253944666.

The spelling of 20531523 in words is "twenty million, five hundred thirty-one thousand, five hundred twenty-three".