645656194 has 4 divisors (see below), whose sum is σ = 968484294. Its totient is φ = 322828096.

The previous prime is 645656191. The next prime is 645656201. The reversal of 645656194 is 491656546.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 509630625 + 136025569 = 22575^2 + 11663^2 .

It is not an unprimeable number, because it can be changed into a prime (645656191) 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, 161414047 + ... + 161414050.

Almost surely, 2^645656194 is an apocalyptic number.

645656194 is a deficient number, since it is larger than the sum of its proper divisors (322828100).

645656194 is a wasteful number, since it uses less digits than its factorization.

645656194 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322828099.

The product of its digits is 777600, while the sum is 46.

The square root of 645656194 is about 25409.7657210766. The cubic root of 645656194 is about 864.3051628735.

The spelling of 645656194 in words is "six hundred forty-five million, six hundred fifty-six thousand, one hundred ninety-four".