645214561 has 4 divisors (see below), whose sum is σ = 673267392. Its totient is φ = 617161732.

The previous prime is 645214553. The next prime is 645214571. The reversal of 645214561 is 165412546.

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.

It is a cyclic number.

It is not a de Polignac number, because 645214561 - 2³ = 645214553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645214511) 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, 14026381 + ... + 14026426.

It is an arithmetic number, because the mean of its divisors is an integer number (168316848).

Almost surely, 2^645214561 is an apocalyptic number.

It is an amenable number.

645214561 is a deficient number, since it is larger than the sum of its proper divisors (28052831).

645214561 is a wasteful number, since it uses less digits than its factorization.

645214561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28052830.

The product of its digits is 28800, while the sum is 34.

The square root of 645214561 is about 25401.0740127263. The cubic root of 645214561 is about 864.1080544906.

The spelling of 645214561 in words is "six hundred forty-five million, two hundred fourteen thousand, five hundred sixty-one".