21073918 has 16 divisors (see below), whose sum is σ = 32550336. Its totient is φ = 10226560.

The previous prime is 21073909. The next prime is 21073919. The reversal of 21073918 is 81937012.

It is a super-2 number, since 2×21073918² = 888220039741448, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21073918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21073919) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18555 + ... + 19657.

It is an arithmetic number, because the mean of its divisors is an integer number (2034396).

Almost surely, 2^21073918 is an apocalyptic number.

21073918 is a deficient number, since it is larger than the sum of its proper divisors (11476418).

21073918 is a wasteful number, since it uses less digits than its factorization.

21073918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1379.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21073918 is about 4590.6337253151. The cubic root of 21073918 is about 276.2157435870.

The spelling of 21073918 in words is "twenty-one million, seventy-three thousand, nine hundred eighteen".