665162157221 has 2 divisors, whose sum is σ = 665162157222. Its totient is φ = 665162157220.

The previous prime is 665162157217. The next prime is 665162157251. The reversal of 665162157221 is 122751261566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644023905121 + 21138252100 = 802511^2 + 145390^2 .

It is a cyclic number.

It is not a de Polignac number, because 665162157221 - 2² = 665162157217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665162157251) 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, 332581078610 + 332581078611.

It is an arithmetic number, because the mean of its divisors is an integer number (332581078611).

Almost surely, 2^665162157221 is an apocalyptic number.

It is an amenable number.

665162157221 is a deficient number, since it is larger than the sum of its proper divisors (1).

665162157221 is an equidigital number, since it uses as much as digits as its factorization.

665162157221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 302400, while the sum is 44.

The spelling of 665162157221 in words is "six hundred sixty-five billion, one hundred sixty-two million, one hundred fifty-seven thousand, two hundred twenty-one".