61328978865 has 144 divisors (see below), whose sum is σ = 134447040000. Its totient is φ = 25313967360.

The previous prime is 61328978857. The next prime is 61328978869. The reversal of 61328978865 is 56887982316.

61328978865 is a `hidden beast` number, since 613 + 2 + 8 + 9 + 7 + 8 + 8 + 6 + 5 = 666.

It is not a de Polignac number, because 61328978865 - 2³ = 61328978857 is a prime.

It is a super-2 number, since 2×61328978865² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (61328978869) 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 143 ways as a sum of consecutive naturals, for example, 5673736 + ... + 5684534.

It is an arithmetic number, because the mean of its divisors is an integer number (933660000).

Almost surely, 2^61328978865 is an apocalyptic number.

It is an amenable number.

61328978865 is an abundant number, since it is smaller than the sum of its proper divisors (73118061135).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61328978865 is a wasteful number, since it uses less digits than its factorization.

61328978865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10988 (or 10974 counting only the distinct ones).

The product of its digits is 34836480, while the sum is 63.

The spelling of 61328978865 in words is "sixty-one billion, three hundred twenty-eight million, nine hundred seventy-eight thousand, eight hundred sixty-five".