645670777 has 4 divisors (see below), whose sum is σ = 647621776. Its totient is φ = 643719780.

The previous prime is 645670733. The next prime is 645670801. The reversal of 645670777 is 777076546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 777076546 = 2 ⋅388538273.

It is a cyclic number.

It is not a de Polignac number, because 645670777 - 2²³ = 637282169 is a prime.

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 645670777.

It is not an unprimeable number, because it can be changed into a prime (645670717) 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 in 3 ways as a sum of consecutive naturals, for example, 975003 + ... + 975664.

It is an arithmetic number, because the mean of its divisors is an integer number (161905444).

Almost surely, 2^645670777 is an apocalyptic number.

It is an amenable number.

645670777 is a deficient number, since it is larger than the sum of its proper divisors (1950999).

645670777 is a wasteful number, since it uses less digits than its factorization.

645670777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1950998.

The product of its (nonzero) digits is 1728720, while the sum is 49.

The square root of 645670777 is about 25410.0526760572. The cubic root of 645670777 is about 864.3116699833.

The spelling of 645670777 in words is "six hundred forty-five million, six hundred seventy thousand, seven hundred seventy-seven".