20563531 has 4 divisors (see below), whose sum is σ = 20580912. Its totient is φ = 20546152.

The previous prime is 20563519. The next prime is 20563537. The reversal of 20563531 is 13536502.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20563531 - 2²¹ = 18466379 is a prime.

It is a super-2 number, since 2×20563531² = 845717614375922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20563496 and 20563505.

It is not an unprimeable number, because it can be changed into a prime (20563537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6775 + ... + 9328.

It is an arithmetic number, because the mean of its divisors is an integer number (5145228).

Almost surely, 2^20563531 is an apocalyptic number.

20563531 is a deficient number, since it is larger than the sum of its proper divisors (17381).

20563531 is a wasteful number, since it uses less digits than its factorization.

20563531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17380.

The product of its (nonzero) digits is 2700, while the sum is 25.

The square root of 20563531 is about 4534.7029671192. The cubic root of 20563531 is about 273.9676156515.

It can be divided in two parts, 205 and 63531, that added together give a palindrome (63736).

The spelling of 20563531 in words is "twenty million, five hundred sixty-three thousand, five hundred thirty-one".