8541219721 has 2 divisors, whose sum is σ = 8541219722. Its totient is φ = 8541219720.

The previous prime is 8541219703. The next prime is 8541219761. The reversal of 8541219721 is 1279121458.

It is an a-pointer prime, because the next prime (8541219761) can be obtained adding 8541219721 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8448367225 + 92852496 = 91915^2 + 9636^2 .

It is a cyclic number.

It is not a de Polignac number, because 8541219721 - 2⁷ = 8541219593 is a prime.

It is not a weakly prime, because it can be changed into another prime (8541219761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4270609860 + 4270609861.

It is an arithmetic number, because the mean of its divisors is an integer number (4270609861).

Almost surely, 2^8541219721 is an apocalyptic number.

It is an amenable number.

8541219721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8541219721 is an equidigital number, since it uses as much as digits as its factorization.

8541219721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 40.

The square root of 8541219721 is about 92418.7195377646. The cubic root of 8541219721 is about 2044.1211480980.

The spelling of 8541219721 in words is "eight billion, five hundred forty-one million, two hundred nineteen thousand, seven hundred twenty-one".