66387421 has 2 divisors, whose sum is σ = 66387422. Its totient is φ = 66387420.

The previous prime is 66387403. The next prime is 66387437. The reversal of 66387421 is 12478366.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66096900 + 290521 = 8130^2 + 539^2 .

It is a cyclic number.

It is not a de Polignac number, because 66387421 - 2⁹ = 66386909 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66387481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33193710 + 33193711.

It is an arithmetic number, because the mean of its divisors is an integer number (33193711).

Almost surely, 2^66387421 is an apocalyptic number.

It is an amenable number.

66387421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66387421 is an equidigital number, since it uses as much as digits as its factorization.

66387421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 37.

The square root of 66387421 is about 8147.8476298959. The cubic root of 66387421 is about 404.9131978786.

The spelling of 66387421 in words is "sixty-six million, three hundred eighty-seven thousand, four hundred twenty-one".