61394432840 has 128 divisors (see below), whose sum is σ = 149846306400. Its totient is φ = 22504366080.

The previous prime is 61394432833. The next prime is 61394432857. The reversal of 61394432840 is 4823449316.

It is a Cunningham number, because it is equal to 247779²-1.

It can be written as a sum of positive squares in 16 ways, for example, as 5118257764 + 56276175076 = 71542^2 + 237226^2 .

It is a junction number, because it is equal to n+sod(n) for n = 61394432791 and 61394432800.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 64421804 + ... + 64422756.

Almost surely, 2^61394432840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61394432840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (74923153200).

61394432840 is an abundant number, since it is smaller than the sum of its proper divisors (88451873560).

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

61394432840 is a wasteful number, since it uses less digits than its factorization.

61394432840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1747 (or 1743 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 44.

The spelling of 61394432840 in words is "sixty-one billion, three hundred ninety-four million, four hundred thirty-two thousand, eight hundred forty".