9997700821 has 4 divisors (see below), whose sum is σ = 10007398944. Its totient is φ = 9988002700.

The previous prime is 9997700809. The next prime is 9997700827. The reversal of 9997700821 is 1280077999.

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: 1280077999 = 3251 ⋅393749.

It is a cyclic number.

It is not a de Polignac number, because 9997700821 - 2¹³ = 9997692629 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 (9997700827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4847515 + ... + 4849576.

It is an arithmetic number, because the mean of its divisors is an integer number (2501849736).

Almost surely, 2^9997700821 is an apocalyptic number.

It is an amenable number.

9997700821 is a deficient number, since it is larger than the sum of its proper divisors (9698123).

9997700821 is a wasteful number, since it uses less digits than its factorization.

9997700821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9698122.

The product of its (nonzero) digits is 571536, while the sum is 52.

The square root of 9997700821 is about 99988.5034441460. The cubic root of 9997700821 is about 2154.2695630095.

The spelling of 9997700821 in words is "nine billion, nine hundred ninety-seven million, seven hundred thousand, eight hundred twenty-one".