126810991 has 4 divisors (see below), whose sum is σ = 129903984. Its totient is φ = 123718000.

The previous prime is 126810979. The next prime is 126811019. The reversal of 126810991 is 199018621.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 126810991 - 2¹⁹ = 126286703 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 126810991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126810911) 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, 1546435 + ... + 1546516.

It is an arithmetic number, because the mean of its divisors is an integer number (32475996).

Almost surely, 2^126810991 is an apocalyptic number.

126810991 is a deficient number, since it is larger than the sum of its proper divisors (3092993).

126810991 is an equidigital number, since it uses as much as digits as its factorization.

126810991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3092992.

The product of its (nonzero) digits is 7776, while the sum is 37.

The square root of 126810991 is about 11261.0386288299. The cubic root of 126810991 is about 502.4030865139.

The spelling of 126810991 in words is "one hundred twenty-six million, eight hundred ten thousand, nine hundred ninety-one".