645426091 has 2 divisors, whose sum is σ = 645426092. Its totient is φ = 645426090.

The previous prime is 645426079. The next prime is 645426203. The reversal of 645426091 is 190624546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645426091 - 2¹⁷ = 645295019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645426091.

It is not a weakly prime, because it can be changed into another prime (645426031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322713045 + 322713046.

It is an arithmetic number, because the mean of its divisors is an integer number (322713046).

Almost surely, 2^645426091 is an apocalyptic number.

645426091 is a deficient number, since it is larger than the sum of its proper divisors (1).

645426091 is an equidigital number, since it uses as much as digits as its factorization.

645426091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 645426091 is about 25405.2374718285. The cubic root of 645426091 is about 864.2024751772.

The spelling of 645426091 in words is "six hundred forty-five million, four hundred twenty-six thousand, ninety-one".