251666065 has 24 divisors (see below), whose sum is σ = 348626880. Its totient is φ = 170844960.

The previous prime is 251666027. The next prime is 251666081. The reversal of 251666065 is 560666152.

It is not a de Polignac number, because 251666065 - 2⁹ = 251665553 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 600426 + ... + 600844.

It is an arithmetic number, because the mean of its divisors is an integer number (14526120).

Almost surely, 2^251666065 is an apocalyptic number.

It is an amenable number.

251666065 is a deficient number, since it is larger than the sum of its proper divisors (96960815).

251666065 is an equidigital number, since it uses as much as digits as its factorization.

251666065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 693 (or 562 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 251666065 is about 15863.9864157783. The cubic root of 251666065 is about 631.3568346448.

The spelling of 251666065 in words is "two hundred fifty-one million, six hundred sixty-six thousand, sixty-five".