126005681 has 4 divisors (see below), whose sum is σ = 127253364. Its totient is φ = 124758000.

The previous prime is 126005653. The next prime is 126005713. The reversal of 126005681 is 186500621.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 122855056 + 3150625 = 11084^2 + 1775^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-126005681 is a prime.

It is a super-2 number, since 2×126005681² = 31754863288547522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (126005611) 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, 623690 + ... + 623891.

It is an arithmetic number, because the mean of its divisors is an integer number (31813341).

Almost surely, 2^126005681 is an apocalyptic number.

It is an amenable number.

126005681 is a deficient number, since it is larger than the sum of its proper divisors (1247683).

126005681 is a wasteful number, since it uses less digits than its factorization.

126005681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1247682.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 126005681 is about 11225.2252093221. The cubic root of 126005681 is about 501.3373279191.

It can be divided in two parts, 12600 and 5681, that added together give a palindrome (18281).

The spelling of 126005681 in words is "one hundred twenty-six million, five thousand, six hundred eighty-one".