6420656641 has 9 divisors (see below), whose sum is σ = 7469579649. Its totient is φ = 5502939204.

The previous prime is 6420656633. The next prime is 6420656717. The reversal of 6420656641 is 1466560246.

The square root of 6420656641 is 80129.

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

It is not a de Polignac number, because 6420656641 - 2³ = 6420656633 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6420656594 and 6420656603.

It is not an unprimeable number, because it can be changed into a prime (6420656141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 555180 + ... + 566626.

Almost surely, 2^6420656641 is an apocalyptic number.

6420656641 is the 80129-th square number.

6420656641 is the 40065-th centered octagonal number.

It is an amenable number.

6420656641 is a deficient number, since it is larger than the sum of its proper divisors (1048923008).

6420656641 is an frugal number, since it uses more digits than its factorization.

6420656641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22908 (or 11454 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 40.

The cubic root of 6420656641 is about 1858.6308806340.

The spelling of 6420656641 in words is "six billion, four hundred twenty million, six hundred fifty-six thousand, six hundred forty-one".