21856578086 has 64 divisors (see below), whose sum is σ = 39680409600. Its totient is φ = 9015804000.

The previous prime is 21856578077. The next prime is 21856578089. The reversal of 21856578086 is 68087565812.

It is a happy number.

It is a super-3 number, since 3×21856578086³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21856578089) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4059116 + ... + 4064496.

It is an arithmetic number, because the mean of its divisors is an integer number (620006400).

Almost surely, 2^21856578086 is an apocalyptic number.

21856578086 is a deficient number, since it is larger than the sum of its proper divisors (17823831514).

21856578086 is a wasteful number, since it uses less digits than its factorization.

21856578086 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5626 (or 5612 counting only the distinct ones).

The product of its (nonzero) digits is 6451200, while the sum is 56.

The spelling of 21856578086 in words is "twenty-one billion, eight hundred fifty-six million, five hundred seventy-eight thousand, eighty-six".