645840001 has 16 divisors (see below), whose sum is σ = 701373760. Its totient is φ = 592764480.

The previous prime is 645839993. The next prime is 645840007. The reversal of 645840001 is 100048546.

It is a cyclic number.

It is not a de Polignac number, because 645840001 - 2³ = 645839993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645840007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73495 + ... + 81811.

It is an arithmetic number, because the mean of its divisors is an integer number (43835860).

Almost surely, 2^645840001 is an apocalyptic number.

645840001 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

645840001 is a deficient number, since it is larger than the sum of its proper divisors (55533759).

645840001 is a wasteful number, since it uses less digits than its factorization.

645840001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8464.

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 645840001 is about 25413.3823211315. The cubic root of 645840001 is about 864.3871726012.

Adding to 645840001 its reverse (100048546), we get a palindrome (745888547).

The spelling of 645840001 in words is "six hundred forty-five million, eight hundred forty thousand, one".