8437721 has 4 divisors (see below), whose sum is σ = 8494500. Its totient is φ = 8380944.

The previous prime is 8437669. The next prime is 8437727. The reversal of 8437721 is 1277348.

It is a happy number.

8437721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 2062096 + 6375625 = 1436^2 + 2525^2 .

It is a cyclic number.

It is not a de Polignac number, because 8437721 - 2¹⁸ = 8175577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8437727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28166 + ... + 28463.

It is an arithmetic number, because the mean of its divisors is an integer number (2123625).

Almost surely, 2^8437721 is an apocalyptic number.

It is an amenable number.

8437721 is a deficient number, since it is larger than the sum of its proper divisors (56779).

8437721 is a wasteful number, since it uses less digits than its factorization.

8437721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56778.

The product of its digits is 9408, while the sum is 32.

The square root of 8437721 is about 2904.7755507096. The cubic root of 8437721 is about 203.5830986700.

The spelling of 8437721 in words is "eight million, four hundred thirty-seven thousand, seven hundred twenty-one".