665654251 has 2 divisors, whose sum is σ = 665654252. Its totient is φ = 665654250.

The previous prime is 665654239. The next prime is 665654257. The reversal of 665654251 is 152456566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665654251 - 2¹⁷ = 665523179 is a prime.

It is not a weakly prime, because it can be changed into another prime (665654257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332827125 + 332827126.

It is an arithmetic number, because the mean of its divisors is an integer number (332827126).

Almost surely, 2^665654251 is an apocalyptic number.

665654251 is a deficient number, since it is larger than the sum of its proper divisors (1).

665654251 is an equidigital number, since it uses as much as digits as its factorization.

665654251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216000, while the sum is 40.

The square root of 665654251 is about 25800.2761806923. The cubic root of 665654251 is about 873.1380274211.

The spelling of 665654251 in words is "six hundred sixty-five million, six hundred fifty-four thousand, two hundred fifty-one".