64131443420521 has 3 divisors (see below), whose sum is σ = 64131451428733. Its totient is φ = 64131435412310.

The previous prime is 64131443420503. The next prime is 64131443420531. The reversal of 64131443420521 is 12502434413146.

The square root of 64131443420521 is 8008211.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 64131443420521 - 2¹⁹ = 64131442896233 is a prime.

It is a super-2 number, since 2×64131443420521² (a number of 28 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64131443420531) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4004106 + ... + 12012316.

Almost surely, 2^{64131443420521} is an apocalyptic number.

64131443420521 is the 8008211-st square number.

64131443420521 is the 4004106-th centered octagonal number.

It is an amenable number.

64131443420521 is a deficient number, since it is larger than the sum of its proper divisors (8008212).

64131443420521 is an frugal number, since it uses more digits than its factorization.

64131443420521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16016422 (or 8008211 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 40.

Adding to 64131443420521 its reverse (12502434413146), we get a palindrome (76633877833667).

The spelling of 64131443420521 in words is "sixty-four trillion, one hundred thirty-one billion, four hundred forty-three million, four hundred twenty thousand, five hundred twenty-one".