4220721 has 16 divisors (see below), whose sum is σ = 6289920. Its totient is φ = 2797200.

The previous prime is 4220719. The next prime is 4220729. The reversal of 4220721 is 1270224.

It is not a de Polignac number, because 4220721 - 2¹ = 4220719 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 4220694 and 4220703.

It is not an unprimeable number, because it can be changed into a prime (4220729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5671 + ... + 6371.

It is an arithmetic number, because the mean of its divisors is an integer number (393120).

Almost surely, 2^4220721 is an apocalyptic number.

It is an amenable number.

4220721 is a deficient number, since it is larger than the sum of its proper divisors (2069199).

4220721 is a wasteful number, since it uses less digits than its factorization.

4220721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 933 (or 927 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 4220721 is about 2054.4393395766. The cubic root of 4220721 is about 161.6077616317.

Adding to 4220721 its reverse (1270224), we get a palindrome (5490945).

The spelling of 4220721 in words is "four million, two hundred twenty thousand, seven hundred twenty-one".