61516778400 has 720 divisors, whose sum is σ = 279718971840. Its totient is φ = 12781670400.

The previous prime is 61516778377. The next prime is 61516778423. The reversal of 61516778400 is 487761516.

61516778400 is a `hidden beast` number, since 6 + 15 + 167 + 78 + 400 = 666.

61516778400 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (61516778377) and next prime (61516778423).

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 4983436 + ... + 4995764.

It is an arithmetic number, because the mean of its divisors is an integer number (388498572).

Almost surely, 2^61516778400 is an apocalyptic number.

61516778400 is a gapful number since it is divisible by the number (60) 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 61516778400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139859485920).

61516778400 is an abundant number, since it is smaller than the sum of its proper divisors (218202193440).

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

61516778400 is a wasteful number, since it uses less digits than its factorization.

61516778400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12379 (or 12357 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The spelling of 61516778400 in words is "sixty-one billion, five hundred sixteen million, seven hundred seventy-eight thousand, four hundred".