126139781 has 2 divisors, whose sum is σ = 126139782. Its totient is φ = 126139780.

The previous prime is 126139777. The next prime is 126139883. The reversal of 126139781 is 187931621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 105062500 + 21077281 = 10250^2 + 4591^2 .

It is a cyclic number.

It is not a de Polignac number, because 126139781 - 2² = 126139777 is a prime.

It is a super-2 number, since 2×126139781² = 31822488701455922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (126339781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63069890 + 63069891.

It is an arithmetic number, because the mean of its divisors is an integer number (63069891).

Almost surely, 2^126139781 is an apocalyptic number.

It is an amenable number.

126139781 is a deficient number, since it is larger than the sum of its proper divisors (1).

126139781 is an equidigital number, since it uses as much as digits as its factorization.

126139781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 38.

The square root of 126139781 is about 11231.1967750547. The cubic root of 126139781 is about 501.5151122325.

The spelling of 126139781 in words is "one hundred twenty-six million, one hundred thirty-nine thousand, seven hundred eighty-one".