21518079 has 8 divisors (see below), whose sum is σ = 31299072. Its totient is φ = 13041240.

The previous prime is 21518059. The next prime is 21518083. The reversal of 21518079 is 97081512.

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

It is not a de Polignac number, because 21518079 - 2⁵ = 21518047 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 652063 = 21518079 / (2 + 1 + 5 + 1 + 8 + 0 + 7 + 9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518009) 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, 325999 + ... + 326064.

It is an arithmetic number, because the mean of its divisors is an integer number (3912384).

Almost surely, 2^21518079 is an apocalyptic number.

21518079 is a deficient number, since it is larger than the sum of its proper divisors (9780993).

21518079 is a wasteful number, since it uses less digits than its factorization.

21518079 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652077.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 21518079 is about 4638.7583467993. The cubic root of 21518079 is about 278.1428065694.

The spelling of 21518079 in words is "twenty-one million, five hundred eighteen thousand, seventy-nine".