645517243 has 8 divisors (see below), whose sum is σ = 755727840. Its totient is φ = 539805120.

The previous prime is 645517237. The next prime is 645517259. The reversal of 645517243 is 342715546.

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 645517243 - 2⁵ = 645517211 is a prime.

It is a super-2 number, since 2×645517243² = 833385022020642098, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (645517283) 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, 1124308 + ... + 1124881.

It is an arithmetic number, because the mean of its divisors is an integer number (94465980).

Almost surely, 2^645517243 is an apocalyptic number.

645517243 is a deficient number, since it is larger than the sum of its proper divisors (110210597).

645517243 is a wasteful number, since it uses less digits than its factorization.

645517243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2249237.

The product of its digits is 100800, while the sum is 37.

The square root of 645517243 is about 25407.0313692883. The cubic root of 645517243 is about 864.2431563525.

The spelling of 645517243 in words is "six hundred forty-five million, five hundred seventeen thousand, two hundred forty-three".