4155721 has 2 divisors, whose sum is σ = 4155722. Its totient is φ = 4155720.

The previous prime is 4155703. The next prime is 4155731. The reversal of 4155721 is 1275514.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2295225 + 1860496 = 1515^2 + 1364^2 .

It is a cyclic number.

It is not a de Polignac number, because 4155721 - 2¹⁵ = 4122953 is a prime.

4155721 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (4155731) 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, 2077860 + 2077861.

It is an arithmetic number, because the mean of its divisors is an integer number (2077861).

Almost surely, 2^4155721 is an apocalyptic number.

It is an amenable number.

4155721 is a deficient number, since it is larger than the sum of its proper divisors (1).

4155721 is an equidigital number, since it uses as much as digits as its factorization.

4155721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1400, while the sum is 25.

The square root of 4155721 is about 2038.5585593747. The cubic root of 4155721 is about 160.7738682030.

The spelling of 4155721 in words is "four million, one hundred fifty-five thousand, seven hundred twenty-one".