71668021 has 2 divisors, whose sum is σ = 71668022. Its totient is φ = 71668020.

The previous prime is 71667991. The next prime is 71668043. The reversal of 71668021 is 12086617.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68657796 + 3010225 = 8286^2 + 1735^2 .

It is a cyclic number.

It is not a de Polignac number, because 71668021 - 2⁵ = 71667989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71668061) 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 as a sum of consecutive naturals, namely, 35834010 + 35834011.

It is an arithmetic number, because the mean of its divisors is an integer number (35834011).

Almost surely, 2^71668021 is an apocalyptic number.

It is an amenable number.

71668021 is a deficient number, since it is larger than the sum of its proper divisors (1).

71668021 is an equidigital number, since it uses as much as digits as its factorization.

71668021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 71668021 is about 8465.6967226567. The cubic root of 71668021 is about 415.3763866480.

The spelling of 71668021 in words is "seventy-one million, six hundred sixty-eight thousand, twenty-one".