645388001 has 4 divisors (see below), whose sum is σ = 645440532. Its totient is φ = 645335472.

The previous prime is 645387971. The next prime is 645388031. The reversal of 645388001 is 100883546.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 100883546 = 2 ⋅50441773.

It is an interprime number because it is at equal distance from previous prime (645387971) and next prime (645388031).

It can be written as a sum of positive squares in 2 ways, for example, as 120978001 + 524410000 = 10999^2 + 22900^2 .

It is a cyclic number.

It is not a de Polignac number, because 645388001 - 2⁶ = 645387937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645388031) 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, 3131 + ... + 36063.

It is an arithmetic number, because the mean of its divisors is an integer number (161360133).

Almost surely, 2^645388001 is an apocalyptic number.

It is an amenable number.

645388001 is a deficient number, since it is larger than the sum of its proper divisors (52531).

645388001 is a wasteful number, since it uses less digits than its factorization.

645388001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52530.

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 645388001 is about 25404.4878121957. The cubic root of 645388001 is about 864.1854744597.

The spelling of 645388001 in words is "six hundred forty-five million, three hundred eighty-eight thousand, one".