21075918 has 8 divisors (see below), whose sum is σ = 42151848. Its totient is φ = 7025304.

The previous prime is 21075917. The next prime is 21075919. The reversal of 21075918 is 81957012.

It is an interprime number because it is at equal distance from previous prime (21075917) and next prime (21075919).

It is a sphenic number, since it is the product of 3 distinct primes.

21075918 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075917) 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 in 3 ways as a sum of consecutive naturals, for example, 1756321 + ... + 1756332.

It is an arithmetic number, because the mean of its divisors is an integer number (5268981).

Almost surely, 2^21075918 is an apocalyptic number.

21075918 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21075918 is a wasteful number, since it uses less digits than its factorization.

21075918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3512658.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 21075918 is about 4590.8515549950. The cubic root of 21075918 is about 276.2244813075.

The spelling of 21075918 in words is "twenty-one million, seventy-five thousand, nine hundred eighteen".