126278021 has 2 divisors, whose sum is σ = 126278022. Its totient is φ = 126278020.

The previous prime is 126278017. The next prime is 126278039. The reversal of 126278021 is 120872621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120450625 + 5827396 = 10975^2 + 2414^2 .

It is a cyclic number.

It is not a de Polignac number, because 126278021 - 2² = 126278017 is a prime.

It is a super-2 number, since 2×126278021² = 31892277175352882, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (126278071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63139010 + 63139011.

It is an arithmetic number, because the mean of its divisors is an integer number (63139011).

Almost surely, 2^126278021 is an apocalyptic number.

It is an amenable number.

126278021 is a deficient number, since it is larger than the sum of its proper divisors (1).

126278021 is an equidigital number, since it uses as much as digits as its factorization.

126278021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 126278021 is about 11237.3493760762. The cubic root of 126278021 is about 501.6982533407.

The spelling of 126278021 in words is "one hundred twenty-six million, two hundred seventy-eight thousand, twenty-one".