126505991 has 2 divisors, whose sum is σ = 126505992. Its totient is φ = 126505990.

The previous prime is 126505979. The next prime is 126506011. The reversal of 126505991 is 199505621.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 126505991 - 2⁶ = 126505927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (126505901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63252995 + 63252996.

It is an arithmetic number, because the mean of its divisors is an integer number (63252996).

Almost surely, 2^126505991 is an apocalyptic number.

126505991 is a deficient number, since it is larger than the sum of its proper divisors (1).

126505991 is an equidigital number, since it uses as much as digits as its factorization.

126505991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24300, while the sum is 38.

The square root of 126505991 is about 11247.4882084846. The cubic root of 126505991 is about 501.9999775136. Note that the first 4 decimals are identical.

The spelling of 126505991 in words is "one hundred twenty-six million, five hundred five thousand, nine hundred ninety-one".