126521 has 4 divisors (see below), whose sum is σ = 133200. Its totient is φ = 119844.

The previous prime is 126517. The next prime is 126541. The reversal of 126521 is 125621.

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 a cyclic number.

It is not a de Polignac number, because 126521 - 2² = 126517 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 126521.

It is not an unprimeable number, because it can be changed into a prime (126541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3311 + ... + 3348.

It is an arithmetic number, because the mean of its divisors is an integer number (33300).

2¹²⁶⁵²¹ is an apocalyptic number.

It is an amenable number.

126521 is a deficient number, since it is larger than the sum of its proper divisors (6679).

126521 is an equidigital number, since it uses as much as digits as its factorization.

126521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6678.

The product of its digits is 120, while the sum is 17.

The square root of 126521 is about 355.6979055322. The cubic root of 126521 is about 50.2019829590.

Subtracting from 126521 its reverse (125621), we obtain a square (900 = 30²).

It can be divided in two parts, 1265 and 21, that multiplied together give a triangular number (26565 = T₂₃₀).

The spelling of 126521 in words is "one hundred twenty-six thousand, five hundred twenty-one".