646880795521 has 9 divisors (see below), whose sum is σ = 682735195233. Its totient is φ = 612819960660.

The previous prime is 646880795497. The next prime is 646880795527. The reversal of 646880795521 is 125597088646.

The square root of 646880795521 is 804289.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 646880795521 - 2²⁹ = 646343924609 is a prime.

It is a super-2 number, since 2×646880795521² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 646880795521.

It is not an unprimeable number, because it can be changed into a prime (646880795527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 15260326 + ... + 15302656.

It is an arithmetic number, because the mean of its divisors is an integer number (75859466137).

Almost surely, 2^646880795521 is an apocalyptic number.

646880795521 is the 804289-th square number.

646880795521 is the 402145-th centered octagonal number.

It is an amenable number.

646880795521 is a deficient number, since it is larger than the sum of its proper divisors (35854399712).

646880795521 is an frugal number, since it uses more digits than its factorization.

646880795521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84700 (or 42350 counting only the distinct ones).

The product of its (nonzero) digits is 29030400, while the sum is 61.

It can be divided in two parts, 646880 and 795521, that added together give a square (1442401 = 1201²).

The spelling of 646880795521 in words is "six hundred forty-six billion, eight hundred eighty million, seven hundred ninety-five thousand, five hundred twenty-one".