21681068 has 6 divisors (see below), whose sum is σ = 37941876. Its totient is φ = 10840532.

The previous prime is 21681061. The next prime is 21681091. The reversal of 21681068 is 86018612.

It is not an unprimeable number, because it can be changed into a prime (21681061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2710130 + ... + 2710137.

It is an arithmetic number, because the mean of its divisors is an integer number (6323646).

Almost surely, 2^21681068 is an apocalyptic number.

It is an amenable number.

21681068 is a deficient number, since it is larger than the sum of its proper divisors (16260808).

21681068 is a wasteful number, since it uses less digits than its factorization.

21681068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5420271 (or 5420269 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21681068 is about 4656.2933756369. The cubic root of 21681068 is about 278.8433064542.

The spelling of 21681068 in words is "twenty-one million, six hundred eighty-one thousand, sixty-eight".