646201561 has 4 divisors (see below), whose sum is σ = 647182800. Its totient is φ = 645220324.

The previous prime is 646201547. The next prime is 646201579. The reversal of 646201561 is 165102646.

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 646201561 - 2¹³ = 646193369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646201511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489631 + ... + 490948.

It is an arithmetic number, because the mean of its divisors is an integer number (161795700).

Almost surely, 2^646201561 is an apocalyptic number.

It is an amenable number.

646201561 is a deficient number, since it is larger than the sum of its proper divisors (981239).

646201561 is an equidigital number, since it uses as much as digits as its factorization.

646201561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 981238.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 646201561 is about 25420.4949007686. The cubic root of 646201561 is about 864.5484455290.

The spelling of 646201561 in words is "six hundred forty-six million, two hundred one thousand, five hundred sixty-one".