21089918 has 8 divisors (see below), whose sum is σ = 31829448. Its totient is φ = 10480104.

The previous prime is 21089903. The next prime is 21089921. The reversal of 21089918 is 81998012.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32021 + ... + 32672.

It is an arithmetic number, because the mean of its divisors is an integer number (3978681).

Almost surely, 2^21089918 is an apocalyptic number.

21089918 is a deficient number, since it is larger than the sum of its proper divisors (10739530).

21089918 is a wasteful number, since it uses less digits than its factorization.

21089918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64858.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 21089918 is about 4592.3760734504. The cubic root of 21089918 is about 276.2856298781.

The spelling of 21089918 in words is "twenty-one million, eighty-nine thousand, nine hundred eighteen".