9715561021 has 6 divisors (see below), whose sum is σ = 9850479450. Its totient is φ = 9582465888.

The previous prime is 9715561019. The next prime is 9715561067. The reversal of 9715561021 is 1201655179.

9715561021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 1673955396 + 8041605625 = 40914^2 + 89675^2 .

It is not a de Polignac number, because 9715561021 - 2¹ = 9715561019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9715511021) 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 in 5 ways as a sum of consecutive naturals, for example, 906246 + ... + 916903.

It is an arithmetic number, because the mean of its divisors is an integer number (1641746575).

Almost surely, 2^9715561021 is an apocalyptic number.

It is an amenable number.

9715561021 is a deficient number, since it is larger than the sum of its proper divisors (134918429).

9715561021 is an equidigital number, since it uses as much as digits as its factorization.

9715561021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1823295 (or 1823222 counting only the distinct ones).

The product of its (nonzero) digits is 18900, while the sum is 37.

The square root of 9715561021 is about 98567.5454751715. The cubic root of 9715561021 is about 2133.8110572038.

The spelling of 9715561021 in words is "nine billion, seven hundred fifteen million, five hundred sixty-one thousand, twenty-one".