1665390165251 has 2 divisors, whose sum is σ = 1665390165252. Its totient is φ = 1665390165250.

The previous prime is 1665390165181. The next prime is 1665390165253. The reversal of 1665390165251 is 1525610935661.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1665390165251 - 2²² = 1665385970947 is a prime.

Together with 1665390165253, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1665390165251.

It is not a weakly prime, because it can be changed into another prime (1665390165253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832695082625 + 832695082626.

It is an arithmetic number, because the mean of its divisors is an integer number (832695082626).

Almost surely, 2^{1665390165251} is an apocalyptic number.

1665390165251 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665390165251 is an equidigital number, since it uses as much as digits as its factorization.

1665390165251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458000, while the sum is 50.

The spelling of 1665390165251 in words is "one trillion, six hundred sixty-five billion, three hundred ninety million, one hundred sixty-five thousand, two hundred fifty-one".