126509731 has 4 divisors (see below), whose sum is σ = 128111200. Its totient is φ = 124908264.

The previous prime is 126509711. The next prime is 126509749. The reversal of 126509731 is 137905621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 137905621 = 7 ⋅19700803.

It is a cyclic number.

It is not a de Polignac number, because 126509731 - 2²⁵ = 92955299 is a prime.

It is a super-2 number, since 2×126509731² = 32009424075384722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (126509701) 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 in 3 ways as a sum of consecutive naturals, for example, 800616 + ... + 800773.

It is an arithmetic number, because the mean of its divisors is an integer number (32027800).

Almost surely, 2^126509731 is an apocalyptic number.

126509731 is a deficient number, since it is larger than the sum of its proper divisors (1601469).

126509731 is an equidigital number, since it uses as much as digits as its factorization.

126509731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1601468.

The product of its (nonzero) digits is 11340, while the sum is 34.

The square root of 126509731 is about 11247.6544665988. The cubic root of 126509731 is about 502.0049244767.

The spelling of 126509731 in words is "one hundred twenty-six million, five hundred nine thousand, seven hundred thirty-one".