671643431521 has 16 divisors (see below), whose sum is σ = 704121528960. Its totient is φ = 639440081280.

The previous prime is 671643431507. The next prime is 671643431593. The reversal of 671643431521 is 125134346176.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 671643431521 - 2⁵ = 671643431489 is a prime.

It is a super-2 number, since 2×671643431521² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (671643431021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18906586 + ... + 18942076.

It is an arithmetic number, because the mean of its divisors is an integer number (44007595560).

Almost surely, 2^671643431521 is an apocalyptic number.

It is an amenable number.

671643431521 is a deficient number, since it is larger than the sum of its proper divisors (32478097439).

671643431521 is a wasteful number, since it uses less digits than its factorization.

671643431521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39336.

The product of its digits is 362880, while the sum is 43.

Adding to 671643431521 its reverse (125134346176), we get a palindrome (796777777697).

The spelling of 671643431521 in words is "six hundred seventy-one billion, six hundred forty-three million, four hundred thirty-one thousand, five hundred twenty-one".