66040421 has 2 divisors, whose sum is σ = 66040422. Its totient is φ = 66040420.

The previous prime is 66040417. The next prime is 66040423. The reversal of 66040421 is 12404066.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49140100 + 16900321 = 7010^2 + 4111^2 .

It is a cyclic number.

It is not a de Polignac number, because 66040421 - 2² = 66040417 is a prime.

It is a super-2 number, since 2×66040421² = 8722674411714482, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 66040423, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66040423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33020210 + 33020211.

It is an arithmetic number, because the mean of its divisors is an integer number (33020211).

Almost surely, 2^66040421 is an apocalyptic number.

It is an amenable number.

66040421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66040421 is an equidigital number, since it uses as much as digits as its factorization.

66040421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 66040421 is about 8126.5257644334. The cubic root of 66040421 is about 404.2064857121.

Adding to 66040421 its reverse (12404066), we get a palindrome (78444487).

It can be divided in two parts, 660 and 40421, that multiplied together give a triangular number (26677860 = T₇₃₀₄).

The spelling of 66040421 in words is "sixty-six million, forty thousand, four hundred twenty-one".