126242021 has 4 divisors (see below), whose sum is σ = 127492044. Its totient is φ = 124992000.

The previous prime is 126241967. The next prime is 126242027. The reversal of 126242021 is 120242621.

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 110481121 + 15760900 = 10511^2 + 3970^2 .

It is a cyclic number.

It is not a de Polignac number, because 126242021 - 2¹⁴ = 126225637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 126241984 and 126242002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126242027) 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, 624860 + ... + 625061.

It is an arithmetic number, because the mean of its divisors is an integer number (31873011).

Almost surely, 2^126242021 is an apocalyptic number.

It is an amenable number.

126242021 is a deficient number, since it is larger than the sum of its proper divisors (1250023).

126242021 is a wasteful number, since it uses less digits than its factorization.

126242021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1250022.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 126242021 is about 11235.7474606721. The cubic root of 126242021 is about 501.6505732203.

Adding to 126242021 its reverse (120242621), we get a palindrome (246484642).

The spelling of 126242021 in words is "one hundred twenty-six million, two hundred forty-two thousand, twenty-one".