9872521 has 2 divisors, whose sum is σ = 9872522. Its totient is φ = 9872520.

The previous prime is 9872519. The next prime is 9872567. The reversal of 9872521 is 1252789.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9834496 + 38025 = 3136^2 + 195^2 .

It is a cyclic number.

It is not a de Polignac number, because 9872521 - 2¹ = 9872519 is a prime.

Together with 9872519, it forms a pair of twin primes.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (9872501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4936260 + 4936261.

It is an arithmetic number, because the mean of its divisors is an integer number (4936261).

Almost surely, 2^9872521 is an apocalyptic number.

9872521 is the 1680-th centered heptagonal number.

It is an amenable number.

9872521 is a deficient number, since it is larger than the sum of its proper divisors (1).

9872521 is an equidigital number, since it uses as much as digits as its factorization.

9872521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 34.

The square root of 9872521 is about 3142.0568104348. The cubic root of 9872521 is about 214.5240671173.

The spelling of 9872521 in words is "nine million, eight hundred seventy-two thousand, five hundred twenty-one".