66694421 has 2 divisors, whose sum is σ = 66694422. Its totient is φ = 66694420.

The previous prime is 66694393. The next prime is 66694429. The reversal of 66694421 is 12449666.

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., 65383396 + 1311025 = 8086^2 + 1145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66694421 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 (66694429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33347210 + 33347211.

It is an arithmetic number, because the mean of its divisors is an integer number (33347211).

Almost surely, 2^66694421 is an apocalyptic number.

It is an amenable number.

66694421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66694421 is an equidigital number, since it uses as much as digits as its factorization.

66694421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 38.

The square root of 66694421 is about 8166.6652312924. The cubic root of 66694421 is about 405.5363943853.

The spelling of 66694421 in words is "sixty-six million, six hundred ninety-four thousand, four hundred twenty-one".