126156721 has 2 divisors, whose sum is σ = 126156722. Its totient is φ = 126156720.

The previous prime is 126156707. The next prime is 126156749. The reversal of 126156721 is 127651621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 124010496 + 2146225 = 11136^2 + 1465^2 .

It is an emirp because it is prime and its reverse (127651621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 126156721 - 2⁹ = 126156209 is a prime.

It is not a weakly prime, because it can be changed into another prime (126156761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63078360 + 63078361.

It is an arithmetic number, because the mean of its divisors is an integer number (63078361).

Almost surely, 2^126156721 is an apocalyptic number.

It is an amenable number.

126156721 is a deficient number, since it is larger than the sum of its proper divisors (1).

126156721 is an equidigital number, since it uses as much as digits as its factorization.

126156721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 31.

The square root of 126156721 is about 11231.9508991092. The cubic root of 126156721 is about 501.5375616286.

The spelling of 126156721 in words is "one hundred twenty-six million, one hundred fifty-six thousand, seven hundred twenty-one".