126636721 has 2 divisors, whose sum is σ = 126636722. Its totient is φ = 126636720.

The previous prime is 126636673. The next prime is 126636733. The reversal of 126636721 is 127636621.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74580496 + 52056225 = 8636^2 + 7215^2 .

It is a cyclic number.

It is not a de Polignac number, because 126636721 - 2²³ = 118248113 is a prime.

It is not a weakly prime, because it can be changed into another prime (126636221) 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, 63318360 + 63318361.

It is an arithmetic number, because the mean of its divisors is an integer number (63318361).

Almost surely, 2^126636721 is an apocalyptic number.

It is an amenable number.

126636721 is a deficient number, since it is larger than the sum of its proper divisors (1).

126636721 is an equidigital number, since it uses as much as digits as its factorization.

126636721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 34.

The square root of 126636721 is about 11253.2982276309. The cubic root of 126636721 is about 502.1728385341.

The spelling of 126636721 in words is "one hundred twenty-six million, six hundred thirty-six thousand, seven hundred twenty-one".