665550091 has 2 divisors, whose sum is σ = 665550092. Its totient is φ = 665550090.

The previous prime is 665550049. The next prime is 665550101. The reversal of 665550091 is 190055566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665550091 - 2⁹ = 665549579 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 665550091.

It is not a weakly prime, because it can be changed into another prime (665550491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332775045 + 332775046.

It is an arithmetic number, because the mean of its divisors is an integer number (332775046).

Almost surely, 2^665550091 is an apocalyptic number.

665550091 is a deficient number, since it is larger than the sum of its proper divisors (1).

665550091 is an equidigital number, since it uses as much as digits as its factorization.

665550091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40500, while the sum is 37.

The square root of 665550091 is about 25798.2575186775. The cubic root of 665550091 is about 873.0924828556.

The spelling of 665550091 in words is "six hundred sixty-five million, five hundred fifty thousand, ninety-one".