7551721 has 4 divisors (see below), whose sum is σ = 7949200. Its totient is φ = 7154244.

The previous prime is 7551707. The next prime is 7551743. The reversal of 7551721 is 1271557.

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 7551721 - 2⁹ = 7551209 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7551721.

It is not an unprimeable number, because it can be changed into a prime (7551781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198711 + ... + 198748.

It is an arithmetic number, because the mean of its divisors is an integer number (1987300).

Almost surely, 2^7551721 is an apocalyptic number.

It is an amenable number.

7551721 is a deficient number, since it is larger than the sum of its proper divisors (397479).

7551721 is a wasteful number, since it uses less digits than its factorization.

7551721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397478.

The product of its digits is 2450, while the sum is 28.

The square root of 7551721 is about 2748.0394829769. The cubic root of 7551721 is about 196.1923091680.

The spelling of 7551721 in words is "seven million, five hundred fifty-one thousand, seven hundred twenty-one".