1242721 has 4 divisors (see below), whose sum is σ = 1245744. Its totient is φ = 1239700.

The previous prime is 1242643. The next prime is 1242739. The reversal of 1242721 is 1272421.

It is a happy number.

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 1242721 - 2¹⁹ = 718433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1242781) 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 in 3 ways as a sum of consecutive naturals, for example, 775 + ... + 1756.

It is an arithmetic number, because the mean of its divisors is an integer number (311436).

2^1242721 is an apocalyptic number.

It is an amenable number.

1242721 is a deficient number, since it is larger than the sum of its proper divisors (3023).

1242721 is an equidigital number, since it uses as much as digits as its factorization.

1242721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3022.

The product of its digits is 224, while the sum is 19.

The square root of 1242721 is about 1114.7739681209. The cubic root of 1242721 is about 107.5122322479.

The spelling of 1242721 in words is "one million, two hundred forty-two thousand, seven hundred twenty-one".