646464561 has 4 divisors (see below), whose sum is σ = 861952752. Its totient is φ = 430976372.

The previous prime is 646464557. The next prime is 646464563. The reversal of 646464561 is 165464646.

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 646464561 - 2² = 646464557 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (646464563) 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, 107744091 + ... + 107744096.

It is an arithmetic number, because the mean of its divisors is an integer number (215488188).

Almost surely, 2^646464561 is an apocalyptic number.

It is an amenable number.

646464561 is a deficient number, since it is larger than the sum of its proper divisors (215488191).

646464561 is a wasteful number, since it uses less digits than its factorization.

646464561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215488190.

The product of its digits is 414720, while the sum is 42.

The square root of 646464561 is about 25425.6673658726. The cubic root of 646464561 is about 864.6657182269.

The spelling of 646464561 in words is "six hundred forty-six million, four hundred sixty-four thousand, five hundred sixty-one".