1002721 has 2 divisors, whose sum is σ = 1002722. Its totient is φ = 1002720.

The previous prime is 1002719. The next prime is 1002739. The reversal of 1002721 is 1272001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 810000 + 192721 = 900^2 + 439^2 .

It is an emirp because it is prime and its reverse (1272001) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1002721 - 2¹ = 1002719 is a prime.

Together with 1002719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1002751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 501360 + 501361.

It is an arithmetic number, because the mean of its divisors is an integer number (501361).

2^1002721 is an apocalyptic number.

It is an amenable number.

1002721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1002721 is an equidigital number, since it uses as much as digits as its factorization.

1002721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 1002721 is about 1001.3595757769. The cubic root of 1002721 is about 100.0906178592.

Adding to 1002721 its reverse (1272001), we get a palindrome (2274722).

The spelling of 1002721 in words is "one million, two thousand, seven hundred twenty-one".