645440243 has 8 divisors (see below), whose sum is σ = 761441280. Its totient is φ = 535388040.

The previous prime is 645440239. The next prime is 645440249. The reversal of 645440243 is 342044546.

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 645440243 - 2² = 645440239 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645440249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1486973 + ... + 1487406.

It is an arithmetic number, because the mean of its divisors is an integer number (95180160).

Almost surely, 2^645440243 is an apocalyptic number.

645440243 is a deficient number, since it is larger than the sum of its proper divisors (116001037).

645440243 is a wasteful number, since it uses less digits than its factorization.

645440243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2974417.

The product of its (nonzero) digits is 46080, while the sum is 32.

The square root of 645440243 is about 25405.5159955471. The cubic root of 645440243 is about 864.2087914718.

Adding to 645440243 its reverse (342044546), we get a palindrome (987484789).

The spelling of 645440243 in words is "six hundred forty-five million, four hundred forty thousand, two hundred forty-three".