645909547 has 16 divisors (see below), whose sum is σ = 680666400. Its totient is φ = 612057600.

The previous prime is 645909527. The next prime is 645909557. The reversal of 645909547 is 745909546.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 645909547 - 2¹¹ = 645907499 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645909547.

It is not an unprimeable number, because it can be changed into a prime (645909527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 778729 + ... + 779557.

It is an arithmetic number, because the mean of its divisors is an integer number (42541650).

Almost surely, 2^645909547 is an apocalyptic number.

645909547 is a gapful number since it is divisible by the number (67) formed by its first and last digit.

645909547 is a deficient number, since it is larger than the sum of its proper divisors (34756853).

645909547 is a wasteful number, since it uses less digits than its factorization.

645909547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1326.

The product of its (nonzero) digits is 1360800, while the sum is 49.

The square root of 645909547 is about 25414.7505791420. The cubic root of 645909547 is about 864.4181980939.

Subtracting 645909547 from its reverse (745909546), we obtain a palindrome (99999999).

The spelling of 645909547 in words is "six hundred forty-five million, nine hundred nine thousand, five hundred forty-seven".