671780441521 has 6 divisors (see below), whose sum is σ = 781458881010. Its totient is φ = 575811806976.

The previous prime is 671780441477. The next prime is 671780441531. The reversal of 671780441521 is 125144087176.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 629585119296 + 42195322225 = 793464^2 + 205415^2 .

It is not a de Polignac number, because 671780441521 - 2⁷ = 671780441393 is a prime.

It is a super-2 number, since 2×671780441521² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (671780441531) 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 5 ways as a sum of consecutive naturals, for example, 6854902416 + ... + 6854902513.

It is an arithmetic number, because the mean of its divisors is an integer number (130243146835).

Almost surely, 2^671780441521 is an apocalyptic number.

It is an amenable number.

671780441521 is a deficient number, since it is larger than the sum of its proper divisors (109678439489).

671780441521 is a wasteful number, since it uses less digits than its factorization.

671780441521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13709804943 (or 13709804936 counting only the distinct ones).

The product of its (nonzero) digits is 376320, while the sum is 46.

The spelling of 671780441521 in words is "six hundred seventy-one billion, seven hundred eighty million, four hundred forty-one thousand, five hundred twenty-one".