645442055431 has 4 divisors (see below), whose sum is σ = 645444293200. Its totient is φ = 645439817664.

The previous prime is 645442055399. The next prime is 645442055507. The reversal of 645442055431 is 134550244546.

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 645442055431 - 2⁵ = 645442055399 is a prime.

It is a super-2 number, since 2×645442055431² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645442055131) 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, 608691 + ... + 1288948.

It is an arithmetic number, because the mean of its divisors is an integer number (161361073300).

Almost surely, 2^645442055431 is an apocalyptic number.

645442055431 is a deficient number, since it is larger than the sum of its proper divisors (2237769).

645442055431 is a wasteful number, since it uses less digits than its factorization.

645442055431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2237768.

The product of its (nonzero) digits is 1152000, while the sum is 43.

Adding to 645442055431 its reverse (134550244546), we get a palindrome (779992299977).

The spelling of 645442055431 in words is "six hundred forty-five billion, four hundred forty-two million, fifty-five thousand, four hundred thirty-one".