126166021 has 4 divisors (see below), whose sum is σ = 126621772. Its totient is φ = 125710272.

The previous prime is 126166009. The next prime is 126166043. The reversal of 126166021 is 120661621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120661621 = 8191 ⋅14731.

It can be written as a sum of positive squares in 2 ways, for example, as 53728900 + 72437121 = 7330^2 + 8511^2 .

It is a cyclic number.

It is not a de Polignac number, because 126166021 - 2⁵ = 126165989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126166321) 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, 227460 + ... + 228013.

It is an arithmetic number, because the mean of its divisors is an integer number (31655443).

Almost surely, 2^126166021 is an apocalyptic number.

It is an amenable number.

126166021 is a deficient number, since it is larger than the sum of its proper divisors (455751).

126166021 is an equidigital number, since it uses as much as digits as its factorization.

126166021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455750.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 126166021 is about 11232.3648890160. The cubic root of 126166021 is about 501.5498854130.

The spelling of 126166021 in words is "one hundred twenty-six million, one hundred sixty-six thousand, twenty-one".