645480181 has 16 divisors (see below), whose sum is σ = 668694400. Its totient is φ = 622702080.

The previous prime is 645480161. The next prime is 645480221. The reversal of 645480181 is 181084546.

It is a cyclic number.

It is not a de Polignac number, because 645480181 - 2⁵ = 645480149 is a prime.

It is a super-2 number, since 2×645480181² = 833289328127585522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645480181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645480131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2062081 + ... + 2062393.

It is an arithmetic number, because the mean of its divisors is an integer number (41793400).

Almost surely, 2^645480181 is an apocalyptic number.

It is an amenable number.

645480181 is a deficient number, since it is larger than the sum of its proper divisors (23214219).

645480181 is a wasteful number, since it uses less digits than its factorization.

645480181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 796.

The product of its (nonzero) digits is 30720, while the sum is 37.

The square root of 645480181 is about 25406.3019937967. The cubic root of 645480181 is about 864.2266160286.

The spelling of 645480181 in words is "six hundred forty-five million, four hundred eighty thousand, one hundred eighty-one".