61681984 has 168 divisors, whose sum is σ = 164180520. Its totient is φ = 22708224.

The previous prime is 61681979. The next prime is 61681993. The reversal of 61681984 is 48918616.

It can be written as a sum of positive squares in 4 ways, for example, as 1960000 + 59721984 = 1400^2 + 7728^2 .

Its product of digits (82944) is a multiple of the sum of its prime divisors (128).

It is a self number, because there is not a number n which added to its sum of digits gives 61681984.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 693012 + ... + 693100.

It is an arithmetic number, because the mean of its divisors is an integer number (977265).

Almost surely, 2^61681984 is an apocalyptic number.

61681984 is a gapful number since it is divisible by the number (64) 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 61681984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82090260).

61681984 is an abundant number, since it is smaller than the sum of its proper divisors (102498536).

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

61681984 is a wasteful number, since it uses less digits than its factorization.

61681984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 128 counting only the distinct ones).

The product of its digits is 82944, while the sum is 43.

The square root of 61681984 is about 7853.7878759233. The cubic root of 61681984 is about 395.1112948151. Note that the first 3 decimals are identical.

The spelling of 61681984 in words is "sixty-one million, six hundred eighty-one thousand, nine hundred eighty-four".