4247721 has 15 divisors (see below), whose sum is σ = 6373191. Its totient is φ = 2819448.

The previous prime is 4247707. The next prime is 4247729. The reversal of 4247721 is 1277424.

It is a happy number.

The square root of 4247721 is 2061.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 3956121 + 291600 = 1989^2 + 540^2 .

It is not a de Polignac number, because 4247721 - 2⁵ = 4247689 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (4247729) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 18435 + ... + 18663.

Almost surely, 2^4247721 is an apocalyptic number.

4247721 is the 2061-st square number.

4247721 is the 1031-st centered octagonal number.

It is an amenable number.

4247721 is a deficient number, since it is larger than the sum of its proper divisors (2125470).

4247721 is an frugal number, since it uses more digits than its factorization.

4247721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470 (or 232 counting only the distinct ones).

The product of its digits is 3136, while the sum is 27.

The cubic root of 4247721 is about 161.9516316506.

Multiplying 4247721 by its product of digits (3136), we get a square (13320853056 = 115416²).

The spelling of 4247721 in words is "four million, two hundred forty-seven thousand, seven hundred twenty-one".