7721121 has 4 divisors (see below), whose sum is σ = 10294832. Its totient is φ = 5147412.

The previous prime is 7721117. The next prime is 7721143. The reversal of 7721121 is 1211277.

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 not a de Polignac number, because 7721121 - 2² = 7721117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7721101) 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, 1286851 + ... + 1286856.

It is an arithmetic number, because the mean of its divisors is an integer number (2573708).

Almost surely, 2^7721121 is an apocalyptic number.

It is an amenable number.

7721121 is a deficient number, since it is larger than the sum of its proper divisors (2573711).

7721121 is a wasteful number, since it uses less digits than its factorization.

7721121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2573710.

The product of its digits is 196, while the sum is 21.

The square root of 7721121 is about 2778.6905189315. The cubic root of 7721121 is about 197.6484681845.

Adding to 7721121 its reverse (1211277), we get a palindrome (8932398).

The spelling of 7721121 in words is "seven million, seven hundred twenty-one thousand, one hundred twenty-one".