21256043013366 has 16 divisors (see below), whose sum is σ = 48585241173504. Its totient is φ = 6073155146664.

The previous prime is 21256043013329. The next prime is 21256043013367. The reversal of 21256043013366 is 66331034065212.

It is a super-3 number, since 3×21256043013366³ (a number of 41 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 506096262223 = 21256043013366 / (2 + 1 + 2 + 5 + 6 + 0 + 4 + 3 + 0 + 1 + 3 + 3 + 6 + 6).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256043013367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 253048131070 + ... + 253048131153.

It is an arithmetic number, because the mean of its divisors is an integer number (3036577573344).

Almost surely, 2^{21256043013366} is an apocalyptic number.

21256043013366 is an abundant number, since it is smaller than the sum of its proper divisors (27329198160138).

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

21256043013366 is a wasteful number, since it uses less digits than its factorization.

21256043013366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506096262235.

The product of its (nonzero) digits is 466560, while the sum is 42.

Adding to 21256043013366 its reverse (66331034065212), we get a palindrome (87587077078578).

The spelling of 21256043013366 in words is "twenty-one trillion, two hundred fifty-six billion, forty-three million, thirteen thousand, three hundred sixty-six".