65621321605 has 12 divisors (see below), whose sum is σ = 91602008460. Its totient is φ = 44997477504.

The previous prime is 65621321593. The next prime is 65621321609. The reversal of 65621321605 is 50612312656.

It can be written as a sum of positive squares in 2 ways, for example, as 11331389601 + 54289932004 = 106449^2 + 233002^2 .

It is not a de Polignac number, because 65621321605 - 2⁹ = 65621321093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65621321609) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 133920820 + ... + 133921309.

It is an arithmetic number, because the mean of its divisors is an integer number (7633500705).

Almost surely, 2^65621321605 is an apocalyptic number.

It is an amenable number.

65621321605 is a deficient number, since it is larger than the sum of its proper divisors (25980686855).

65621321605 is a wasteful number, since it uses less digits than its factorization.

65621321605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267842148 (or 267842141 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The spelling of 65621321605 in words is "sixty-five billion, six hundred twenty-one million, three hundred twenty-one thousand, six hundred five".