61081028991 has 16 divisors (see below), whose sum is σ = 93610773600. Its totient is φ = 39316523904.

The previous prime is 61081028969. The next prime is 61081029041. The reversal of 61081028991 is 19982018016.

61081028991 is a `hidden beast` number, since 610 + 8 + 1 + 0 + 28 + 9 + 9 + 1 = 666.

It is not a de Polignac number, because 61081028991 - 2⁵ = 61081028959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61081028941) 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, 39003706 + ... + 39005271.

It is an arithmetic number, because the mean of its divisors is an integer number (5850673350).

Almost surely, 2^61081028991 is an apocalyptic number.

61081028991 is a deficient number, since it is larger than the sum of its proper divisors (32529744609).

61081028991 is a wasteful number, since it uses less digits than its factorization.

61081028991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78009015 (or 78009009 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 45.

The spelling of 61081028991 in words is "sixty-one billion, eighty-one million, twenty-eight thousand, nine hundred ninety-one".