645565001 has 4 divisors (see below), whose sum is σ = 645629712. Its totient is φ = 645500292.

The previous prime is 645564991. The next prime is 645565031. The reversal of 645565001 is 100565546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 100565546 = 2 ⋅50282773.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645565001 is a prime.

It is a super-2 number, since 2×645565001² = 833508341032260002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645565031) 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, 13871 + ... + 38516.

It is an arithmetic number, because the mean of its divisors is an integer number (161407428).

Almost surely, 2^645565001 is an apocalyptic number.

It is an amenable number.

645565001 is a deficient number, since it is larger than the sum of its proper divisors (64711).

645565001 is a wasteful number, since it uses less digits than its factorization.

645565001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64710.

The product of its (nonzero) digits is 18000, while the sum is 32.

The square root of 645565001 is about 25407.9712098389. The cubic root of 645565001 is about 864.2644692388.

The spelling of 645565001 in words is "six hundred forty-five million, five hundred sixty-five thousand, one".