645731040 has 48 divisors (see below), whose sum is σ = 2034054288. Its totient is φ = 172194816.

The previous prime is 645731039. The next prime is 645731041. The reversal of 645731040 is 40137546.

It is an interprime number because it is at equal distance from previous prime (645731039) and next prime (645731041).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 645730989 and 645731007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645731041) 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, 672157 + ... + 673116.

It is an arithmetic number, because the mean of its divisors is an integer number (42376131).

Almost surely, 2^645731040 is an apocalyptic number.

645731040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645731040 is an abundant number, since it is smaller than the sum of its proper divisors (1388323248).

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

645731040 is a wasteful number, since it uses less digits than its factorization.

645731040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1345291 (or 1345283 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 30.

The square root of 645731040 is about 25411.2384586033. The cubic root of 645731040 is about 864.3385590190.

Adding to 645731040 its reverse (40137546), we get a palindrome (685868586).

The spelling of 645731040 in words is "six hundred forty-five million, seven hundred thirty-one thousand, forty".