51205121055 has 64 divisors (see below), whose sum is σ = 99550886400. Its totient is φ = 24765730560.

The previous prime is 51205121047. The next prime is 51205121057. The reversal of 51205121055 is 55012150215.

It is not a de Polignac number, because 51205121055 - 2³ = 51205121047 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51205121057) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 565212 + ... + 649518.

It is an arithmetic number, because the mean of its divisors is an integer number (1555482600).

Almost surely, 2^51205121055 is an apocalyptic number.

51205121055 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

51205121055 is a deficient number, since it is larger than the sum of its proper divisors (48345765345).

51205121055 is a wasteful number, since it uses less digits than its factorization.

51205121055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84741 (or 84735 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

The spelling of 51205121055 in words is "fifty-one billion, two hundred five million, one hundred twenty-one thousand, fifty-five".