645711566 has 4 divisors (see below), whose sum is σ = 968567352. Its totient is φ = 322855782.

The previous prime is 645711553. The next prime is 645711569. The reversal of 645711566 is 665117546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 665117546 = 2 ⋅332558773.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645711569) 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, 161427890 + ... + 161427893.

It is an arithmetic number, because the mean of its divisors is an integer number (242141838).

Almost surely, 2^645711566 is an apocalyptic number.

645711566 is a deficient number, since it is larger than the sum of its proper divisors (322855786).

645711566 is a wasteful number, since it uses less digits than its factorization.

645711566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322855785.

The product of its digits is 151200, while the sum is 41.

The square root of 645711566 is about 25410.8552787977. The cubic root of 645711566 is about 864.3298700050.

The spelling of 645711566 in words is "six hundred forty-five million, seven hundred eleven thousand, five hundred sixty-six".