645461861 has 8 divisors (see below), whose sum is σ = 705117504. Its totient is φ = 585969120.

The previous prime is 645461833. The next prime is 645461911. The reversal of 645461861 is 168164546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 645461861 - 2¹⁸ = 645199717 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 (645461161) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32360 + ... + 48353.

It is an arithmetic number, because the mean of its divisors is an integer number (88139688).

Almost surely, 2^645461861 is an apocalyptic number.

It is an amenable number.

645461861 is a deficient number, since it is larger than the sum of its proper divisors (59655643).

645461861 is a wasteful number, since it uses less digits than its factorization.

645461861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81451.

The product of its digits is 138240, while the sum is 41.

The square root of 645461861 is about 25405.9414507709. The cubic root of 645461861 is about 864.2184397996.

The spelling of 645461861 in words is "six hundred forty-five million, four hundred sixty-one thousand, eight hundred sixty-one".