645242053 has 4 divisors (see below), whose sum is σ = 645509260. Its totient is φ = 644974848.

The previous prime is 645242041. The next prime is 645242077. The reversal of 645242053 is 350242546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 350242546 = 2 ⋅175121273.

It can be written as a sum of positive squares in 2 ways, for example, as 619860609 + 25381444 = 24897^2 + 5038^2 .

It is a cyclic number.

It is not a de Polignac number, because 645242053 - 2¹⁷ = 645110981 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 (645242453) 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, 129948 + ... + 134821.

It is an arithmetic number, because the mean of its divisors is an integer number (161377315).

Almost surely, 2^645242053 is an apocalyptic number.

It is an amenable number.

645242053 is a deficient number, since it is larger than the sum of its proper divisors (267207).

645242053 is a wasteful number, since it uses less digits than its factorization.

645242053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267206.

The product of its (nonzero) digits is 28800, while the sum is 31.

The square root of 645242053 is about 25401.6151651819. The cubic root of 645242053 is about 864.1203272666.

Adding to 645242053 its reverse (350242546), we get a palindrome (995484599).

The spelling of 645242053 in words is "six hundred forty-five million, two hundred forty-two thousand, fifty-three".