100181561 has 6 divisors (see below), whose sum is σ = 106421550. Its totient is φ = 94288256.

The previous prime is 100181539. The next prime is 100181563. The reversal of 100181561 is 165181001.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 52998400 + 47183161 = 7280^2 + 6869^2 .

It is a de Polignac number, because none of the positive numbers 2^k-100181561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100181563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 173036 + ... + 173613.

It is an arithmetic number, because the mean of its divisors is an integer number (17736925).

Almost surely, 2^100181561 is an apocalyptic number.

It is an amenable number.

100181561 is a deficient number, since it is larger than the sum of its proper divisors (6239989).

100181561 is an equidigital number, since it uses as much as digits as its factorization.

100181561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346683 (or 346666 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 23.

The square root of 100181561 is about 10009.0739331868. The cubic root of 100181561 is about 464.4396240280.

The spelling of 100181561 in words is "one hundred million, one hundred eighty-one thousand, five hundred sixty-one".