51216779520 has 216 divisors, whose sum is σ = 183768975936. Its totient is φ = 13657724928.

The previous prime is 51216779519. The next prime is 51216779521. The reversal of 51216779520 is 2597761215.

51216779520 is a `hidden beast` number, since 51 + 2 + 1 + 6 + 7 + 79 + 520 = 666.

It is an interprime number because it is at equal distance from previous prime (51216779519) and next prime (51216779521).

It is a tau number, because it is divible by the number of its divisors (216).

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

It is not an unprimeable number, because it can be changed into a prime (51216779521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 228709 + ... + 393371.

It is an arithmetic number, because the mean of its divisors is an integer number (850782296).

Almost surely, 2^51216779520 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 51216779520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91884487968).

51216779520 is an abundant number, since it is smaller than the sum of its proper divisors (132552196416).

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

51216779520 is an equidigital number, since it uses as much as digits as its factorization.

51216779520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164699 (or 164673 counting only the distinct ones).

The product of its (nonzero) digits is 264600, while the sum is 45.

The spelling of 51216779520 in words is "fifty-one billion, two hundred sixteen million, seven hundred seventy-nine thousand, five hundred twenty".