126978509 has 4 divisors (see below), whose sum is σ = 145118304. Its totient is φ = 108838716.

The previous prime is 126978493. The next prime is 126978521. The reversal of 126978509 is 905879621.

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.

It is not a de Polignac number, because 126978509 - 2⁴ = 126978493 is a prime.

It is a super-2 number, since 2×126978509² = 32247083495726162, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126978209) 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, 9069887 + ... + 9069900.

It is an arithmetic number, because the mean of its divisors is an integer number (36279576).

Almost surely, 2^126978509 is an apocalyptic number.

It is an amenable number.

126978509 is a deficient number, since it is larger than the sum of its proper divisors (18139795).

126978509 is an equidigital number, since it uses as much as digits as its factorization.

126978509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18139794.

The product of its (nonzero) digits is 272160, while the sum is 47.

The square root of 126978509 is about 11268.4741203057. The cubic root of 126978509 is about 502.6242148968.

The spelling of 126978509 in words is "one hundred twenty-six million, nine hundred seventy-eight thousand, five hundred nine".