65561602500 has 225 divisors, whose sum is σ = 214547226817. Its totient is φ = 17452368000.

The previous prime is 65561602409. The next prime is 65561602507. The reversal of 65561602500 is 520616556.

It is a happy number.

The square root of 65561602500 is 256050.

It is a perfect power (a square), and thus also a powerful number.

65561602500 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 7 ways, for example, as 64387032516 + 1174569984 = 253746^2 + 34272^2 .

It is a tau number, because it is divible by the number of its divisors (225).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65561602507) by changing a digit.

It is a polite number, since it can be written in 74 ways as a sum of consecutive naturals, for example, 115222216 + ... + 115222784.

Almost surely, 2^65561602500 is an apocalyptic number.

65561602500 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

65561602500 is the 256050-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65561602500

65561602500 is an abundant number, since it is smaller than the sum of its proper divisors (148985624317).

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

65561602500 is an frugal number, since it uses more digits than its factorization.

65561602500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1174 (or 579 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

Multiplying 65561602500 by its sum of digits (36), we get a square (2360217690000 = 1536300²).

65561602500 divided by its sum of digits (36) gives a square (1821155625 = 42675²).

The spelling of 65561602500 in words is "sixty-five billion, five hundred sixty-one million, six hundred two thousand, five hundred".