9902127721 has 2 divisors, whose sum is σ = 9902127722. Its totient is φ = 9902127720.

The previous prime is 9902127713. The next prime is 9902127773. The reversal of 9902127721 is 1277212099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5103102096 + 4799025625 = 71436^2 + 69275^2 .

It is an emirp because it is prime and its reverse (1277212099) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9902127721 - 2³ = 9902127713 is a prime.

It is not a weakly prime, because it can be changed into another prime (9902127421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4951063860 + 4951063861.

It is an arithmetic number, because the mean of its divisors is an integer number (4951063861).

Almost surely, 2^9902127721 is an apocalyptic number.

It is an amenable number.

9902127721 is a deficient number, since it is larger than the sum of its proper divisors (1).

9902127721 is an equidigital number, since it uses as much as digits as its factorization.

9902127721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31752, while the sum is 40.

The square root of 9902127721 is about 99509.4353365549. The cubic root of 9902127721 is about 2147.3829864375.

The spelling of 9902127721 in words is "nine billion, nine hundred two million, one hundred twenty-seven thousand, seven hundred twenty-one".