4129721 has 2 divisors, whose sum is σ = 4129722. Its totient is φ = 4129720.

The previous prime is 4129667. The next prime is 4129729. The reversal of 4129721 is 1279214.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2839225 + 1290496 = 1685^2 + 1136^2 .

It is a cyclic number.

It is not a de Polignac number, because 4129721 - 2¹⁰ = 4128697 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (4129729) 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 as a sum of consecutive naturals, namely, 2064860 + 2064861.

It is an arithmetic number, because the mean of its divisors is an integer number (2064861).

Almost surely, 2^4129721 is an apocalyptic number.

It is an amenable number.

4129721 is a deficient number, since it is larger than the sum of its proper divisors (1).

4129721 is an equidigital number, since it uses as much as digits as its factorization.

4129721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 26.

The square root of 4129721 is about 2032.1714986684. The cubic root of 4129721 is about 160.4378760810.

The spelling of 4129721 in words is "four million, one hundred twenty-nine thousand, seven hundred twenty-one".