21820387658256 has 120 divisors (see below), whose sum is σ = 66620658817440. Its totient is φ = 6612005030400.

The previous prime is 21820387658231. The next prime is 21820387658273. The reversal of 21820387658256 is 65285678302812.

21820387658256 is a `hidden beast` number, since 2 + 18 + 2 + 0 + 38 + 7 + 6 + 582 + 5 + 6 = 666.

It is a super-2 number, since 2×21820387658256² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21820387658193 and 21820387658202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 47559391 + ... + 48016001.

It is an arithmetic number, because the mean of its divisors is an integer number (555172156812).

Almost surely, 2^{21820387658256} is an apocalyptic number.

It is an amenable number.

21820387658256 is an abundant number, since it is smaller than the sum of its proper divisors (44800271159184).

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

21820387658256 is a wasteful number, since it uses less digits than its factorization.

21820387658256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486805 (or 486796 counting only the distinct ones).

The product of its (nonzero) digits is 77414400, while the sum is 63.

The spelling of 21820387658256 in words is "twenty-one trillion, eight hundred twenty billion, three hundred eighty-seven million, six hundred fifty-eight thousand, two hundred fifty-six".