665390651 has 2 divisors, whose sum is σ = 665390652. Its totient is φ = 665390650.

The previous prime is 665390639. The next prime is 665390653. The reversal of 665390651 is 156093566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665390651 - 2¹⁴ = 665374267 is a prime.

Together with 665390653, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 665390599 and 665390608.

It is not a weakly prime, because it can be changed into another prime (665390653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332695325 + 332695326.

It is an arithmetic number, because the mean of its divisors is an integer number (332695326).

Almost surely, 2^665390651 is an apocalyptic number.

665390651 is a deficient number, since it is larger than the sum of its proper divisors (1).

665390651 is an equidigital number, since it uses as much as digits as its factorization.

665390651 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145800, while the sum is 41.

The square root of 665390651 is about 25795.1672024044. The cubic root of 665390651 is about 873.0227575837.

The spelling of 665390651 in words is "six hundred sixty-five million, three hundred ninety thousand, six hundred fifty-one".