645606361 has 4 divisors (see below), whose sum is σ = 646358800. Its totient is φ = 644853924.

The previous prime is 645606349. The next prime is 645606373. The reversal of 645606361 is 163606546.

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 an emirpimes, since its reverse is a distinct semiprime: 163606546 = 2 ⋅81803273.

It is an interprime number because it is at equal distance from previous prime (645606349) and next prime (645606373).

It is a cyclic number.

It is not a de Polignac number, because 645606361 - 2²³ = 637217753 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645606361.

It is not an unprimeable number, because it can be changed into a prime (645606461) 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, 374931 + ... + 376648.

It is an arithmetic number, because the mean of its divisors is an integer number (161589700).

Almost surely, 2^645606361 is an apocalyptic number.

It is an amenable number.

645606361 is a deficient number, since it is larger than the sum of its proper divisors (752439).

645606361 is an equidigital number, since it uses as much as digits as its factorization.

645606361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 752438.

The product of its (nonzero) digits is 77760, while the sum is 37.

The square root of 645606361 is about 25408.7851146016. The cubic root of 645606361 is about 864.2829260506.

The spelling of 645606361 in words is "six hundred forty-five million, six hundred six thousand, three hundred sixty-one".