8511721 has 4 divisors (see below), whose sum is σ = 8709712. Its totient is φ = 8313732.

The previous prime is 8511691. The next prime is 8511731. The reversal of 8511721 is 1271158.

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.

It is a cyclic number.

It is not a de Polignac number, because 8511721 - 2⁵ = 8511689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8511731) 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, 98931 + ... + 99016.

It is an arithmetic number, because the mean of its divisors is an integer number (2177428).

Almost surely, 2^8511721 is an apocalyptic number.

It is an amenable number.

8511721 is a deficient number, since it is larger than the sum of its proper divisors (197991).

8511721 is a wasteful number, since it uses less digits than its factorization.

8511721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197990.

The product of its digits is 560, while the sum is 25.

The square root of 8511721 is about 2917.4853898520. The cubic root of 8511721 is about 204.1765180493.

Adding to 8511721 its reverse (1271158), we get a palindrome (9782879).

The spelling of 8511721 in words is "eight million, five hundred eleven thousand, seven hundred twenty-one".