645631544 has 16 divisors (see below), whose sum is σ = 1249609920. Its totient is φ = 312402240.

The previous prime is 645631523. The next prime is 645631549. The reversal of 645631544 is 445136546.

It is a super-3 number, since 3×645631544³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 645631498 and 645631507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645631549) 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, 1301429 + ... + 1301924.

It is an arithmetic number, because the mean of its divisors is an integer number (78100620).

Almost surely, 2^645631544 is an apocalyptic number.

It is an amenable number.

645631544 is a deficient number, since it is larger than the sum of its proper divisors (603978376).

645631544 is a wasteful number, since it uses less digits than its factorization.

645631544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2603390 (or 2603386 counting only the distinct ones).

The product of its digits is 172800, while the sum is 38.

The square root of 645631544 is about 25409.2806667170. The cubic root of 645631544 is about 864.2941635245.

The spelling of 645631544 in words is "six hundred forty-five million, six hundred thirty-one thousand, five hundred forty-four".