645563377 has 4 divisors (see below), whose sum is σ = 659298816. Its totient is φ = 631827940.

The previous prime is 645563353. The next prime is 645563381. The reversal of 645563377 is 773365546.

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: 773365546 = 2 ⋅386682773.

It is a cyclic number.

It is not a de Polignac number, because 645563377 - 2²⁷ = 511345649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645563077) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6867649 + ... + 6867742.

It is an arithmetic number, because the mean of its divisors is an integer number (164824704).

Almost surely, 2^645563377 is an apocalyptic number.

It is an amenable number.

645563377 is a deficient number, since it is larger than the sum of its proper divisors (13735439).

645563377 is a wasteful number, since it uses less digits than its factorization.

645563377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13735438.

The product of its digits is 1587600, while the sum is 46.

The square root of 645563377 is about 25407.9392513443. The cubic root of 645563377 is about 864.2637445162.

The spelling of 645563377 in words is "six hundred forty-five million, five hundred sixty-three thousand, three hundred seventy-seven".