645666047 has 32 divisors (see below), whose sum is σ = 737587200. Its totient is φ = 561116160.

The previous prime is 645666019. The next prime is 645666053. The reversal of 645666047 is 740666546.

It is a cyclic number.

It is not a de Polignac number, because 645666047 - 2²⁶ = 578557183 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645665989 and 645666007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645666347) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3244454 + ... + 3244652.

It is an arithmetic number, because the mean of its divisors is an integer number (23049600).

Almost surely, 2^645666047 is an apocalyptic number.

645666047 is a deficient number, since it is larger than the sum of its proper divisors (91921153).

645666047 is a wasteful number, since it uses less digits than its factorization.

645666047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423.

The product of its (nonzero) digits is 725760, while the sum is 44.

The square root of 645666047 is about 25409.9596024866. The cubic root of 645666047 is about 864.3095594112.

The spelling of 645666047 in words is "six hundred forty-five million, six hundred sixty-six thousand, forty-seven".