61661900240 has 80 divisors (see below), whose sum is σ = 149466290688. Its totient is φ = 23636540928.

The previous prime is 61661900239. The next prime is 61661900269. The reversal of 61661900240 is 4200916616.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 61661900240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13217 + ... + 351423.

Almost surely, 2^61661900240 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 61661900240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (74733145344).

61661900240 is an abundant number, since it is smaller than the sum of its proper divisors (87804390448).

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

61661900240 is a wasteful number, since it uses less digits than its factorization.

61661900240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338316 (or 338310 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The spelling of 61661900240 in words is "sixty-one billion, six hundred sixty-one million, nine hundred thousand, two hundred forty".