5665121280 has 792 divisors, whose sum is σ = 24718212792. Its totient is φ = 1189085184.

The previous prime is 5665121243. The next prime is 5665121281. The reversal of 5665121280 is 821215665.

5665121280 is a `hidden beast` number, since 5 + 66 + 512 + 1 + 2 + 80 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 451584 + 5664669696 = 672^2 + 75264^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5665121281) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 29352864 + ... + 29353056.

Almost surely, 2^5665121280 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 5665121280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12359106396).

5665121280 is an abundant number, since it is smaller than the sum of its proper divisors (19053091512).

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

5665121280 is a wasteful number, since it uses less digits than its factorization.

5665121280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 5665121280 is about 75266.9999402128. Note that the first 4 decimals coincide. The cubic root of 5665121280 is about 1782.6649976075.

The spelling of 5665121280 in words is "five billion, six hundred sixty-five million, one hundred twenty-one thousand, two hundred eighty".