2215921 has 2 divisors, whose sum is σ = 2215922. Its totient is φ = 2215920.

The previous prime is 2215903. The next prime is 2215931. The reversal of 2215921 is 1295122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2146225 + 69696 = 1465^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 2215921 - 2⁷ = 2215793 is a prime.

It is a super-4 number, since 4×2215921⁴ (a number of 26 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 2215892 and 2215901.

It is not a weakly prime, because it can be changed into another prime (2215901) 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 as a sum of consecutive naturals, namely, 1107960 + 1107961.

It is an arithmetic number, because the mean of its divisors is an integer number (1107961).

2^2215921 is an apocalyptic number.

It is an amenable number.

2215921 is a deficient number, since it is larger than the sum of its proper divisors (1).

2215921 is an equidigital number, since it uses as much as digits as its factorization.

2215921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 22.

The square root of 2215921 is about 1488.5969904578. The cubic root of 2215921 is about 130.3721290190.

It can be divided in two parts, 2215 and 921, that added together give a square (3136 = 56²).

The spelling of 2215921 in words is "two million, two hundred fifteen thousand, nine hundred twenty-one".