61081639609 has 9 divisors (see below), whose sum is σ = 61717617871. Its totient is φ = 60452156200.

The previous prime is 61081639571. The next prime is 61081639613. The reversal of 61081639609 is 90693618016.

The square root of 61081639609 is 247147.

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

It can be written as a sum of positive squares in only one way, i.e., 58686516009 + 2395123600 = 242253^2 + 48940^2 .

It is not a de Polignac number, because 61081639609 - 2⁷ = 61081639481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61081639639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 24960624 + ... + 24963070.

Almost surely, 2^61081639609 is an apocalyptic number.

61081639609 is the 247147-th square number.

61081639609 is the 123574-th centered octagonal number.

It is an amenable number.

61081639609 is a deficient number, since it is larger than the sum of its proper divisors (635978262).

61081639609 is an frugal number, since it uses more digits than its factorization.

61081639609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5096 (or 2548 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 49.

Multiplying 61081639609 by its sum of digits (49), we get a square (2993000340841 = 1730029²).

The spelling of 61081639609 in words is "sixty-one billion, eighty-one million, six hundred thirty-nine thousand, six hundred nine".