645551263 has 4 divisors (see below), whose sum is σ = 737772880. Its totient is φ = 553329648.

The previous prime is 645551237. The next prime is 645551267. The reversal of 645551263 is 362155546.

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 645551263 - 2¹³ = 645543071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645551267) 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 3 ways as a sum of consecutive naturals, for example, 46110798 + ... + 46110811.

It is an arithmetic number, because the mean of its divisors is an integer number (184443220).

Almost surely, 2^645551263 is an apocalyptic number.

645551263 is a deficient number, since it is larger than the sum of its proper divisors (92221617).

645551263 is an equidigital number, since it uses as much as digits as its factorization.

645551263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92221616.

The product of its digits is 108000, while the sum is 37.

The square root of 645551263 is about 25407.7008601723. The cubic root of 645551263 is about 864.2583385112.

The spelling of 645551263 in words is "six hundred forty-five million, five hundred fifty-one thousand, two hundred sixty-three".