8502721921 has 4 divisors (see below), whose sum is σ = 9002882052. Its totient is φ = 8002561792.

The previous prime is 8502721861. The next prime is 8502721963. The reversal of 8502721921 is 1291272058.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7750865521 + 751856400 = 88039^2 + 27420^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8502721921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8502721321) 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, 250080040 + ... + 250080073.

It is an arithmetic number, because the mean of its divisors is an integer number (2250720513).

Almost surely, 2^8502721921 is an apocalyptic number.

It is an amenable number.

8502721921 is a deficient number, since it is larger than the sum of its proper divisors (500160131).

8502721921 is a wasteful number, since it uses less digits than its factorization.

8502721921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500160130.

The product of its (nonzero) digits is 20160, while the sum is 37.

The square root of 8502721921 is about 92210.2050805658. The cubic root of 8502721921 is about 2041.0453697244.

Adding to 8502721921 its reverse (1291272058), we get a palindrome (9793993979).

The spelling of 8502721921 in words is "eight billion, five hundred two million, seven hundred twenty-one thousand, nine hundred twenty-one".