126509809 has 4 divisors (see below), whose sum is σ = 133168240. Its totient is φ = 119851380.

The previous prime is 126509807. The next prime is 126509813. The reversal of 126509809 is 908905621.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 908905621 = 13 ⋅69915817.

It is a cyclic number.

It is not a de Polignac number, because 126509809 - 2¹ = 126509807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (126509807) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3329187 + ... + 3329224.

It is an arithmetic number, because the mean of its divisors is an integer number (33292060).

Almost surely, 2^126509809 is an apocalyptic number.

126509809 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

126509809 is a deficient number, since it is larger than the sum of its proper divisors (6658431).

126509809 is an equidigital number, since it uses as much as digits as its factorization.

126509809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6658430.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 126509809 is about 11247.6579339879. The cubic root of 126509809 is about 502.0050276476.

The spelling of 126509809 in words is "one hundred twenty-six million, five hundred nine thousand, eight hundred nine".