126521557 has 2 divisors, whose sum is σ = 126521558. Its totient is φ = 126521556.

The previous prime is 126521543. The next prime is 126521567. The reversal of 126521557 is 755125621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 112338801 + 14182756 = 10599^2 + 3766^2 .

It is a cyclic number.

It is not a de Polignac number, because 126521557 - 2¹¹ = 126519509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (126521567) 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 as a sum of consecutive naturals, namely, 63260778 + 63260779.

It is an arithmetic number, because the mean of its divisors is an integer number (63260779).

Almost surely, 2^126521557 is an apocalyptic number.

It is an amenable number.

126521557 is a deficient number, since it is larger than the sum of its proper divisors (1).

126521557 is an equidigital number, since it uses as much as digits as its factorization.

126521557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21000, while the sum is 34.

The square root of 126521557 is about 11248.1801639199. The cubic root of 126521557 is about 502.0205662913.

It can be divided in two parts, 1265 and 21557, that added together give a palindrome (22822).

The spelling of 126521557 in words is "one hundred twenty-six million, five hundred twenty-one thousand, five hundred fifty-seven".