21784012678 has 16 divisors (see below), whose sum is σ = 34889665536. Its totient is φ = 10176150600.

The previous prime is 21784012673. The next prime is 21784012699. The reversal of 21784012678 is 87621048712.

It is a Harshad number since it is a multiple of its sum of digits (46).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21784012673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5504598 + ... + 5508553.

It is an arithmetic number, because the mean of its divisors is an integer number (2180604096).

Almost surely, 2^21784012678 is an apocalyptic number.

21784012678 is a deficient number, since it is larger than the sum of its proper divisors (13105652858).

21784012678 is a wasteful number, since it uses less digits than its factorization.

21784012678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11013219.

The product of its (nonzero) digits is 301056, while the sum is 46.

The spelling of 21784012678 in words is "twenty-one billion, seven hundred eighty-four million, twelve thousand, six hundred seventy-eight".