9840947821 has 2 divisors, whose sum is σ = 9840947822. Its totient is φ = 9840947820.

The previous prime is 9840947791. The next prime is 9840947839. The reversal of 9840947821 is 1287490489.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9747612900 + 93334921 = 98730^2 + 9661^2 .

It is an emirp because it is prime and its reverse (1287490489) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9840947821 - 2¹⁷ = 9840816749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9840941821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4920473910 + 4920473911.

It is an arithmetic number, because the mean of its divisors is an integer number (4920473911).

Almost surely, 2^9840947821 is an apocalyptic number.

It is an amenable number.

9840947821 is a deficient number, since it is larger than the sum of its proper divisors (1).

9840947821 is an equidigital number, since it uses as much as digits as its factorization.

9840947821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1161216, while the sum is 52.

The square root of 9840947821 is about 99201.5515050042. The cubic root of 9840947821 is about 2142.9513403254.

The spelling of 9840947821 in words is "nine billion, eight hundred forty million, nine hundred forty-seven thousand, eight hundred twenty-one".