9875205721 has 4 divisors (see below), whose sum is σ = 10104861712. Its totient is φ = 9645549732.

The previous prime is 9875205719. The next prime is 9875205731. The reversal of 9875205721 is 1275025789.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1275025789 = 17 ⋅75001517.

It is a cyclic number.

It is not a de Polignac number, because 9875205721 - 2¹ = 9875205719 is a prime.

It is a super-3 number, since 3×9875205721³ (a number of 31 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (9875205731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114827931 + ... + 114828016.

It is an arithmetic number, because the mean of its divisors is an integer number (2526215428).

Almost surely, 2^9875205721 is an apocalyptic number.

It is an amenable number.

9875205721 is a deficient number, since it is larger than the sum of its proper divisors (229655991).

9875205721 is a wasteful number, since it uses less digits than its factorization.

9875205721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229655990.

The product of its (nonzero) digits is 352800, while the sum is 46.

The square root of 9875205721 is about 99374.0696610539. The cubic root of 9875205721 is about 2145.4351115697.

The spelling of 9875205721 in words is "nine billion, eight hundred seventy-five million, two hundred five thousand, seven hundred twenty-one".