61781029128 has 1024 divisors, whose sum is σ = 242694144000. Its totient is φ = 14081900544.

The previous prime is 61781029127. The next prime is 61781029139. The reversal of 61781029128 is 82192018716.

61781029128 is a `hidden beast` number, since 617 + 8 + 1 + 0 + 2 + 9 + 1 + 28 = 666.

It is a super-3 number, since 3×61781029128³ (a number of 33 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (61781029127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 234908725 + ... + 234908987.

It is an arithmetic number, because the mean of its divisors is an integer number (237006000).

Almost surely, 2^61781029128 is an apocalyptic number.

61781029128 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 61781029128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121347072000).

61781029128 is an abundant number, since it is smaller than the sum of its proper divisors (180913114872).

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

61781029128 is a wasteful number, since it uses less digits than its factorization.

61781029128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371 (or 361 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 45.

The spelling of 61781029128 in words is "sixty-one billion, seven hundred eighty-one million, twenty-nine thousand, one hundred twenty-eight".