66801421 has 2 divisors, whose sum is σ = 66801422. Its totient is φ = 66801420.

The previous prime is 66801409. The next prime is 66801431. The reversal of 66801421 is 12410866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 35832196 + 30969225 = 5986^2 + 5565^2 .

It is a cyclic number.

It is not a de Polignac number, because 66801421 - 2⁵ = 66801389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66801421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66801401) 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, 33400710 + 33400711.

It is an arithmetic number, because the mean of its divisors is an integer number (33400711).

Almost surely, 2^66801421 is an apocalyptic number.

It is an amenable number.

66801421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66801421 is an equidigital number, since it uses as much as digits as its factorization.

66801421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 66801421 is about 8173.2136274540. The cubic root of 66801421 is about 405.7531501946.

The spelling of 66801421 in words is "sixty-six million, eight hundred one thousand, four hundred twenty-one".