51210781920 has 72 divisors (see below), whose sum is σ = 174756798216. Its totient is φ = 13656208128.

The previous prime is 51210781877. The next prime is 51210781933. The reversal of 51210781920 is 2918701215.

It is a happy number.

51210781920 is a `hidden beast` number, since 512 + 107 + 8 + 19 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17780082 + ... + 17782961.

It is an arithmetic number, because the mean of its divisors is an integer number (2427177753).

Almost surely, 2^51210781920 is an apocalyptic number.

It is an amenable number.

51210781920 is an abundant number, since it is smaller than the sum of its proper divisors (123546016296).

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

51210781920 is a wasteful number, since it uses less digits than its factorization.

51210781920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35563064 (or 35563053 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 36.

The spelling of 51210781920 in words is "fifty-one billion, two hundred ten million, seven hundred eighty-one thousand, nine hundred twenty".