645451632440 has 64 divisors (see below), whose sum is σ = 1492418584800. Its totient is φ = 251093993472.

The previous prime is 645451632421. The next prime is 645451632451. The reversal of 645451632440 is 44236154546.

It is a junction number, because it is equal to n+sod(n) for n = 645451632391 and 645451632400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 404525 + ... + 1206044.

Almost surely, 2^645451632440 is an apocalyptic number.

It is an amenable number.

645451632440 is an abundant number, since it is smaller than the sum of its proper divisors (846966952360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645451632440 is a wasteful number, since it uses less digits than its factorization.

645451632440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1610856 (or 1610852 counting only the distinct ones).

The product of its (nonzero) digits is 1382400, while the sum is 44.

Adding to 645451632440 its reverse (44236154546), we get a palindrome (689687786986).

The spelling of 645451632440 in words is "six hundred forty-five billion, four hundred fifty-one million, six hundred thirty-two thousand, four hundred forty".