665122993421 has 2 divisors, whose sum is σ = 665122993422. Its totient is φ = 665122993420.

The previous prime is 665122993417. The next prime is 665122993433. The reversal of 665122993421 is 124399221566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 662944437796 + 2178555625 = 814214^2 + 46675^2 .

It is a cyclic number.

It is not a de Polignac number, because 665122993421 - 2² = 665122993417 is a prime.

It is a super-3 number, since 3×665122993421³ (a number of 36 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 665122993421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665122993471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332561496710 + 332561496711.

It is an arithmetic number, because the mean of its divisors is an integer number (332561496711).

Almost surely, 2^665122993421 is an apocalyptic number.

It is an amenable number.

665122993421 is a deficient number, since it is larger than the sum of its proper divisors (1).

665122993421 is an equidigital number, since it uses as much as digits as its factorization.

665122993421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1399680, while the sum is 50.

The spelling of 665122993421 in words is "six hundred sixty-five billion, one hundred twenty-two million, nine hundred ninety-three thousand, four hundred twenty-one".