521856388287378 has 32 divisors (see below), whose sum is σ = 1173997910560320. Its totient is φ = 173952129427668.

The previous prime is 521856388287319. The next prime is 521856388287401. The reversal of 521856388287378 is 873782883658125.

521856388287378 is a `hidden beast` number, since 5 + 2 + 1 + 85 + 6 + 388 + 28 + 73 + 78 = 666.

It is a super-2 number, since 2×521856388287378² (a number of 30 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a junction number, because it is equal to n+sod(n) for n = 521856388287297 and 521856388287306.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59654361000 + ... + 59654369747.

It is an arithmetic number, because the mean of its divisors is an integer number (36687434705010).

Almost surely, 2^{521856388287378} is an apocalyptic number.

521856388287378 is an abundant number, since it is smaller than the sum of its proper divisors (652141522272942).

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

521856388287378 is an equidigital number, since it uses as much as digits as its factorization.

521856388287378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119308730770 (or 119308730752 counting only the distinct ones).

The product of its digits is 8670412800, while the sum is 81.

The spelling of 521856388287378 in words is "five hundred twenty-one trillion, eight hundred fifty-six billion, three hundred eighty-eight million, two hundred eighty-seven thousand, three hundred seventy-eight".