645440763 has 8 divisors (see below), whose sum is σ = 938822976. Its totient is φ = 391176200.

The previous prime is 645440723. The next prime is 645440821. The reversal of 645440763 is 367044546.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645440763 - 2¹² = 645436667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645440713) 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 7 ways as a sum of consecutive naturals, for example, 9779373 + ... + 9779438.

It is an arithmetic number, because the mean of its divisors is an integer number (117352872).

Almost surely, 2^645440763 is an apocalyptic number.

645440763 is a deficient number, since it is larger than the sum of its proper divisors (293382213).

645440763 is a wasteful number, since it uses less digits than its factorization.

645440763 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19558825.

The product of its (nonzero) digits is 241920, while the sum is 39.

The square root of 645440763 is about 25405.5262295431. The cubic root of 645440763 is about 864.2090235555.

The spelling of 645440763 in words is "six hundred forty-five million, four hundred forty thousand, seven hundred sixty-three".