51721654320 has 240 divisors, whose sum is σ = 198848350272. Its totient is φ = 11802101760.

The previous prime is 51721654319. The next prime is 51721654321. The reversal of 51721654320 is 2345612715.

51721654320 is a `hidden beast` number, since 5 + 1 + 7 + 216 + 5 + 432 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (51721654319) and next prime (51721654321).

It is a tau number, because it is divible by the number of its divisors (240).

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

It is not an unprimeable number, because it can be changed into a prime (51721654321) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3081150 + ... + 3097890.

Almost surely, 2^51721654320 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 51721654320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99424175136).

51721654320 is an abundant number, since it is smaller than the sum of its proper divisors (147126695952).

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

51721654320 is a wasteful number, since it uses less digits than its factorization.

51721654320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17380 (or 17371 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

It can be divided in two parts, 517216 and 54320, that added together give a square (571536 = 756²).

The spelling of 51721654320 in words is "fifty-one billion, seven hundred twenty-one million, six hundred fifty-four thousand, three hundred twenty".