8721215 has 4 divisors (see below), whose sum is σ = 10465464. Its totient is φ = 6976968.

The previous prime is 8721197. The next prime is 8721239. The reversal of 8721215 is 5121278.

8721215 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5121278 = 2 ⋅2560639.

It is a cyclic number.

It is not a de Polignac number, because 8721215 - 2¹⁰ = 8720191 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 872117 + ... + 872126.

It is an arithmetic number, because the mean of its divisors is an integer number (2616366).

Almost surely, 2^8721215 is an apocalyptic number.

8721215 is a deficient number, since it is larger than the sum of its proper divisors (1744249).

8721215 is a wasteful number, since it uses less digits than its factorization.

8721215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1744248.

The product of its digits is 1120, while the sum is 26.

The square root of 8721215 is about 2953.1703303399. The cubic root of 8721215 is about 205.8380525653.

The spelling of 8721215 in words is "eight million, seven hundred twenty-one thousand, two hundred fifteen".