126821 has 4 divisors (see below), whose sum is σ = 130944. Its totient is φ = 122700.

The previous prime is 126781. The next prime is 126823. The reversal of 126821 is 128621.

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 126821 - 2⁶ = 126757 is a prime.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 126793 and 126802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126823) 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, 2015 + ... + 2076.

It is an arithmetic number, because the mean of its divisors is an integer number (32736).

2¹²⁶⁸²¹ is an apocalyptic number.

It is an amenable number.

126821 is a deficient number, since it is larger than the sum of its proper divisors (4123).

126821 is an equidigital number, since it uses as much as digits as its factorization.

126821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4122.

The product of its digits is 192, while the sum is 20.

The square root of 126821 is about 356.1193620122. The cubic root of 126821 is about 50.2416304138.

The spelling of 126821 in words is "one hundred twenty-six thousand, eight hundred twenty-one".