21072518 has 8 divisors (see below), whose sum is σ = 31839912. Its totient is φ = 10459216.

The previous prime is 21072517. The next prime is 21072523. The reversal of 21072518 is 81527012.

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 (21072517) 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, 38180 + ... + 38727.

It is an arithmetic number, because the mean of its divisors is an integer number (3979989).

Almost surely, 2^21072518 is an apocalyptic number.

21072518 is a deficient number, since it is larger than the sum of its proper divisors (10767394).

21072518 is a wasteful number, since it uses less digits than its factorization.

21072518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77046.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21072518 is about 4590.4812383888. The cubic root of 21072518 is about 276.2096268538.

The spelling of 21072518 in words is "twenty-one million, seventy-two thousand, five hundred eighteen".