21178068 has 12 divisors (see below), whose sum is σ = 49415520. Its totient is φ = 7059352.

The previous prime is 21178067. The next prime is 21178081. The reversal of 21178068 is 86087112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21178061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 882408 + ... + 882431.

It is an arithmetic number, because the mean of its divisors is an integer number (4117960).

Almost surely, 2^21178068 is an apocalyptic number.

It is an amenable number.

21178068 is an abundant number, since it is smaller than the sum of its proper divisors (28237452).

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

21178068 is a wasteful number, since it uses less digits than its factorization.

21178068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1764846 (or 1764844 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 21178068 is about 4601.9634939882. The cubic root of 21178068 is about 276.6700272168.

The spelling of 21178068 in words is "twenty-one million, one hundred seventy-eight thousand, sixty-eight".