645491556301 has 4 divisors (see below), whose sum is σ = 645559576704. Its totient is φ = 645423535900.

The previous prime is 645491556217. The next prime is 645491556317. The reversal of 645491556301 is 103655194546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 645491556301 - 2²¹ = 645489459149 is a prime.

It is a super-3 number, since 3×645491556301³ (a number of 36 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645491556001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33995965 + ... + 34014946.

It is an arithmetic number, because the mean of its divisors is an integer number (161389894176).

Almost surely, 2^645491556301 is an apocalyptic number.

It is an amenable number.

645491556301 is a deficient number, since it is larger than the sum of its proper divisors (68020403).

645491556301 is an equidigital number, since it uses as much as digits as its factorization.

645491556301 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68020402.

The product of its (nonzero) digits is 1944000, while the sum is 49.

The spelling of 645491556301 in words is "six hundred forty-five billion, four hundred ninety-one million, five hundred fifty-six thousand, three hundred one".