645195042 has 18 divisors (see below), whose sum is σ = 1398156123. Its totient is φ = 215029092.

The previous prime is 645195041. The next prime is 645195073. The reversal of 645195042 is 240591546.

645195042 is a `hidden beast` number, since 645 + 1 + 9 + 5 + 0 + 4 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 322597521 + 322597521 = 17961^2 + 17961^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=17961.

It is a junction number, because it is equal to n+sod(n) for n = 645194988 and 645195006.

It is not an unprimeable number, because it can be changed into a prime (645195041) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 104773 + ... + 110759.

Almost surely, 2^645195042 is an apocalyptic number.

645195042 is an abundant number, since it is smaller than the sum of its proper divisors (752961081).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645195042 is an frugal number, since it uses more digits than its factorization.

645195042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11982 (or 5992 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 645195042 is about 25400.6897937832. The cubic root of 645195042 is about 864.0993407509.

The spelling of 645195042 in words is "six hundred forty-five million, one hundred ninety-five thousand, forty-two".