645234861 has 4 divisors (see below), whose sum is σ = 860313152. Its totient is φ = 430156572.

The previous prime is 645234839. The next prime is 645234871. The reversal of 645234861 is 168432546.

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 not a de Polignac number, because 645234861 - 2⁵ = 645234829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645234871) 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, 107539141 + ... + 107539146.

It is an arithmetic number, because the mean of its divisors is an integer number (215078288).

Almost surely, 2^645234861 is an apocalyptic number.

It is an amenable number.

645234861 is a deficient number, since it is larger than the sum of its proper divisors (215078291).

645234861 is a wasteful number, since it uses less digits than its factorization.

645234861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215078290.

The product of its digits is 138240, while the sum is 39.

The square root of 645234861 is about 25401.4735989863. The cubic root of 645234861 is about 864.1171167006.

The spelling of 645234861 in words is "six hundred forty-five million, two hundred thirty-four thousand, eight hundred sixty-one".