61649491968 has 288 divisors, whose sum is σ = 189744871680. Its totient is φ = 19216465920.

The previous prime is 61649491963. The next prime is 61649491991. The reversal of 61649491968 is 86919494616.

61649491968 is a `hidden beast` number, since 6 + 16 + 49 + 491 + 96 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61649491961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56714721 + ... + 56715807.

It is an arithmetic number, because the mean of its divisors is an integer number (658836360).

Almost surely, 2^61649491968 is an apocalyptic number.

61649491968 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61649491968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94872435840).

61649491968 is an abundant number, since it is smaller than the sum of its proper divisors (128095379712).

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

61649491968 is a wasteful number, since it uses less digits than its factorization.

61649491968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1313 (or 1290 counting only the distinct ones).

The product of its digits is 20155392, while the sum is 63.

The spelling of 61649491968 in words is "sixty-one billion, six hundred forty-nine million, four hundred ninety-one thousand, nine hundred sixty-eight".