665121407 has 2 divisors, whose sum is σ = 665121408. Its totient is φ = 665121406.

The previous prime is 665121389. The next prime is 665121439. The reversal of 665121407 is 704121566.

It is an a-pointer prime, because the next prime (665121439) can be obtained adding 665121407 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665121407 - 2⁶ = 665121343 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 (665121707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332560703 + 332560704.

It is an arithmetic number, because the mean of its divisors is an integer number (332560704).

Almost surely, 2^665121407 is an apocalyptic number.

665121407 is a deficient number, since it is larger than the sum of its proper divisors (1).

665121407 is an equidigital number, since it uses as much as digits as its factorization.

665121407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 665121407 is about 25789.9477897882. The cubic root of 665121407 is about 872.9049882450.

The spelling of 665121407 in words is "six hundred sixty-five million, one hundred twenty-one thousand, four hundred seven".