645650651 has 4 divisors (see below), whose sum is σ = 645790152. Its totient is φ = 645511152.

The previous prime is 645650623. The next prime is 645650683. The reversal of 645650651 is 156056546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645650651 - 2⁶ = 645650587 is a prime.

It is a super-3 number, since 3×645650651³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645650251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62561 + ... + 72146.

It is an arithmetic number, because the mean of its divisors is an integer number (161447538).

Almost surely, 2^645650651 is an apocalyptic number.

645650651 is a deficient number, since it is larger than the sum of its proper divisors (139501).

645650651 is a wasteful number, since it uses less digits than its factorization.

645650651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139500.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 645650651 is about 25409.6566486051. The cubic root of 645650651 is about 864.3026894946.

The spelling of 645650651 in words is "six hundred forty-five million, six hundred fifty thousand, six hundred fifty-one".