100520561 has 4 divisors (see below), whose sum is σ = 102972324. Its totient is φ = 98068800.

The previous prime is 100520551. The next prime is 100520579. The reversal of 100520561 is 165025001.

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 56550400 + 43970161 = 7520^2 + 6631^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100520561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100520521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1225820 + ... + 1225901.

It is an arithmetic number, because the mean of its divisors is an integer number (25743081).

Almost surely, 2^100520561 is an apocalyptic number.

It is an amenable number.

100520561 is a deficient number, since it is larger than the sum of its proper divisors (2451763).

100520561 is an equidigital number, since it uses as much as digits as its factorization.

100520561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2451762.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 100520561 is about 10025.9942649096. The cubic root of 100520561 is about 464.9628998804.

Adding to 100520561 its reverse (165025001), we get a palindrome (265545562).

The spelling of 100520561 in words is "one hundred million, five hundred twenty thousand, five hundred sixty-one".