21085918 has 8 divisors (see below), whose sum is σ = 36147312. Its totient is φ = 9036816.

The previous prime is 21085907. The next prime is 21085919. The reversal of 21085918 is 81958012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21085919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 753055 + ... + 753082.

It is an arithmetic number, because the mean of its divisors is an integer number (4518414).

Almost surely, 2^21085918 is an apocalyptic number.

21085918 is a deficient number, since it is larger than the sum of its proper divisors (15061394).

21085918 is a wasteful number, since it uses less digits than its factorization.

21085918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1506146.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 21085918 is about 4591.9405483956. The cubic root of 21085918 is about 276.2681616200.

The spelling of 21085918 in words is "twenty-one million, eighty-five thousand, nine hundred eighteen".