61553737728 has 320 divisors, whose sum is σ = 210233134320. Its totient is φ = 17581473792.

The previous prime is 61553737711. The next prime is 61553737747. The reversal of 61553737728 is 82773735516.

It is a happy number.

61553737728 is a `hidden beast` number, since 6 + 1 + 5 + 537 + 37 + 72 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 18577800 + ... + 18581112.

Almost surely, 2^61553737728 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 61553737728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105116567160).

61553737728 is an abundant number, since it is smaller than the sum of its proper divisors (148679396592).

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

61553737728 is an frugal number, since it uses more digits than its factorization.

61553737728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3362 (or 3325 counting only the distinct ones).

The product of its digits is 7408800, while the sum is 54.

The spelling of 61553737728 in words is "sixty-one billion, five hundred fifty-three million, seven hundred thirty-seven thousand, seven hundred twenty-eight".