645443550331 has 4 divisors (see below), whose sum is σ = 648144151200. Its totient is φ = 642742949464.

The previous prime is 645443550307. The next prime is 645443550377. The reversal of 645443550331 is 133055344546.

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 645443550331 - 2¹⁷ = 645443419259 is a prime.

It is a super-2 number, since 2×645443550331² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645443550391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1350300076 + ... + 1350300553.

It is an arithmetic number, because the mean of its divisors is an integer number (162036037800).

Almost surely, 2^645443550331 is an apocalyptic number.

645443550331 is a deficient number, since it is larger than the sum of its proper divisors (2700600869).

645443550331 is a wasteful number, since it uses less digits than its factorization.

645443550331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2700600868.

The product of its (nonzero) digits is 1296000, while the sum is 43.

Adding to 645443550331 its reverse (133055344546), we get a palindrome (778498894877).

The spelling of 645443550331 in words is "six hundred forty-five billion, four hundred forty-three million, five hundred fifty thousand, three hundred thirty-one".