7131721 has 4 divisors (see below), whose sum is σ = 7551252. Its totient is φ = 6712192.

The previous prime is 7131703. The next prime is 7131727. The reversal of 7131721 is 1271317.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3111696 + 4020025 = 1764^2 + 2005^2 .

It is a cyclic number.

It is not a de Polignac number, because 7131721 - 2⁵ = 7131689 is a prime.

It is a super-2 number, since 2×7131721² = 101722888843682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 7131692 and 7131701.

It is not an unprimeable number, because it can be changed into a prime (7131727) 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, 209740 + ... + 209773.

It is an arithmetic number, because the mean of its divisors is an integer number (1887813).

Almost surely, 2^7131721 is an apocalyptic number.

It is an amenable number.

7131721 is a deficient number, since it is larger than the sum of its proper divisors (419531).

7131721 is a wasteful number, since it uses less digits than its factorization.

7131721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 419530.

The product of its digits is 294, while the sum is 22.

The square root of 7131721 is about 2670.5282249023. The cubic root of 7131721 is about 192.4855422886.

The spelling of 7131721 in words is "seven million, one hundred thirty-one thousand, seven hundred twenty-one".