21661118 has 8 divisors (see below), whose sum is σ = 32511648. Its totient is φ = 10823904.

The previous prime is 21661109. The next prime is 21661141. The reversal of 21661118 is 81116612.

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 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, 3755 + ... + 7577.

It is an arithmetic number, because the mean of its divisors is an integer number (4063956).

Almost surely, 2^21661118 is an apocalyptic number.

21661118 is a deficient number, since it is larger than the sum of its proper divisors (10850530).

21661118 is a wasteful number, since it uses less digits than its factorization.

21661118 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6658.

The product of its digits is 576, while the sum is 26.

The square root of 21661118 is about 4654.1506206826. The cubic root of 21661118 is about 278.7577536101.

The spelling of 21661118 in words is "twenty-one million, six hundred sixty-one thousand, one hundred eighteen".