646988881617 has 80 divisors (see below), whose sum is σ = 1070212484880. Its totient is φ = 387047351808.

The previous prime is 646988881603. The next prime is 646988881633. The reversal of 646988881617 is 716188889646.

646988881617 is a `hidden beast` number, since 6 + 469 + 8 + 88 + 81 + 6 + 1 + 7 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 91451203281 + 555537678336 = 302409^2 + 745344^2 .

It is not a de Polignac number, because 646988881617 - 2⁴ = 646988881601 is a prime.

It is a super-2 number, since 2×646988881617² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (646988881417) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 6030003 + ... + 6136359.

It is an arithmetic number, because the mean of its divisors is an integer number (13377656061).

Almost surely, 2^646988881617 is an apocalyptic number.

It is an amenable number.

646988881617 is a deficient number, since it is larger than the sum of its proper divisors (423223603263).

646988881617 is a wasteful number, since it uses less digits than its factorization.

646988881617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106544 (or 106535 counting only the distinct ones).

The product of its digits is 222953472, while the sum is 72.

The spelling of 646988881617 in words is "six hundred forty-six billion, nine hundred eighty-eight million, eight hundred eighty-one thousand, six hundred seventeen".