21678894387942 has 64 divisors (see below), whose sum is σ = 47915066868480. Its totient is φ = 6484399862400.

The previous prime is 21678894387823. The next prime is 21678894387959. The reversal of 21678894387942 is 24978349887612.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 5242609 + ... + 8416812.

It is an arithmetic number, because the mean of its divisors is an integer number (748672919820).

Almost surely, 2^{21678894387942} is an apocalyptic number.

21678894387942 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21678894387942 is an abundant number, since it is smaller than the sum of its proper divisors (26236172480538).

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

21678894387942 is a wasteful number, since it uses less digits than its factorization.

21678894387942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13659749.

The product of its digits is 2341011456, while the sum is 78.

The spelling of 21678894387942 in words is "twenty-one trillion, six hundred seventy-eight billion, eight hundred ninety-four million, three hundred eighty-seven thousand, nine hundred forty-two".