8613721 has 4 divisors (see below), whose sum is σ = 8742352. Its totient is φ = 8485092.

The previous prime is 8613701. The next prime is 8613733. The reversal of 8613721 is 1273168.

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 8613721 - 2¹³ = 8605529 is a prime.

It is a Duffinian number.

8613721 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 8613721.

It is not an unprimeable number, because it can be changed into a prime (8613701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64215 + ... + 64348.

It is an arithmetic number, because the mean of its divisors is an integer number (2185588).

Almost surely, 2^8613721 is an apocalyptic number.

It is an amenable number.

8613721 is a deficient number, since it is larger than the sum of its proper divisors (128631).

8613721 is a wasteful number, since it uses less digits than its factorization.

8613721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128630.

The product of its digits is 2016, while the sum is 28.

The square root of 8613721 is about 2934.9141384374. The cubic root of 8613721 is about 204.9888631666.

Adding to 8613721 its reverse (1273168), we get a palindrome (9886889).

The spelling of 8613721 in words is "eight million, six hundred thirteen thousand, seven hundred twenty-one".