645220105 has 8 divisors (see below), whose sum is σ = 777588552. Its totient is φ = 513959808.

The previous prime is 645220087. The next prime is 645220109. The reversal of 645220105 is 501022546.

It can be written as a sum of positive squares in 4 ways, for example, as 6697744 + 638522361 = 2588^2 + 25269^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645220105 - 2⁷ = 645219977 is a prime.

It is a super-2 number, since 2×645220105² = 832617967792422050, 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 645220105.

It is not an unprimeable number, because it can be changed into a prime (645220109) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 275754 + ... + 278083.

It is an arithmetic number, because the mean of its divisors is an integer number (97198569).

Almost surely, 2^645220105 is an apocalyptic number.

It is an amenable number.

645220105 is a deficient number, since it is larger than the sum of its proper divisors (132368447).

645220105 is a wasteful number, since it uses less digits than its factorization.

645220105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554075.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 645220105 is about 25401.1831417357. The cubic root of 645220105 is about 864.1105294303.

The spelling of 645220105 in words is "six hundred forty-five million, two hundred twenty thousand, one hundred five".