100216561 has 2 divisors, whose sum is σ = 100216562. Its totient is φ = 100216560.

The previous prime is 100216511. The next prime is 100216577. The reversal of 100216561 is 165612001.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78872161 + 21344400 = 8881^2 + 4620^2 .

It is a cyclic number.

It is not a de Polignac number, because 100216561 - 2⁷ = 100216433 is a prime.

It is not a weakly prime, because it can be changed into another prime (100216511) 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 as a sum of consecutive naturals, namely, 50108280 + 50108281.

It is an arithmetic number, because the mean of its divisors is an integer number (50108281).

Almost surely, 2^100216561 is an apocalyptic number.

It is an amenable number.

100216561 is a deficient number, since it is larger than the sum of its proper divisors (1).

100216561 is an equidigital number, since it uses as much as digits as its factorization.

100216561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 100216561 is about 10010.8221940058. The cubic root of 100216561 is about 464.4937041535.

Adding to 100216561 its reverse (165612001), we get a palindrome (265828562).

The spelling of 100216561 in words is "one hundred million, two hundred sixteen thousand, five hundred sixty-one".