7215921 has 12 divisors (see below), whose sum is σ = 10494900. Its totient is φ = 4777440.

The previous prime is 7215919. The next prime is 7215941. The reversal of 7215921 is 1295127.

7215921 is a `hidden beast` number, since 72 + 1 + 592 + 1 = 666.

7215921 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 1527696 + 5688225 = 1236^2 + 2385^2 .

It is not a de Polignac number, because 7215921 - 2¹ = 7215919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7215911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1350 + ... + 4031.

It is an arithmetic number, because the mean of its divisors is an integer number (874575).

Almost surely, 2^7215921 is an apocalyptic number.

It is an amenable number.

7215921 is a deficient number, since it is larger than the sum of its proper divisors (3278979).

7215921 is a wasteful number, since it uses less digits than its factorization.

7215921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5536 (or 5533 counting only the distinct ones).

The product of its digits is 1260, while the sum is 27.

The square root of 7215921 is about 2686.2466379690. The cubic root of 7215921 is about 193.2401013681.

The spelling of 7215921 in words is "seven million, two hundred fifteen thousand, nine hundred twenty-one".