21718519 has 8 divisors (see below), whose sum is σ = 22641008. Its totient is φ = 20813760.

The previous prime is 21718513. The next prime is 21718523. The reversal of 21718519 is 91581712.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21718519 - 2⁷ = 21718391 is a prime.

It is a super-2 number, since 2×21718519² = 943388135106722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718513) 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, 1902 + ... + 6859.

It is an arithmetic number, because the mean of its divisors is an integer number (2830126).

Almost surely, 2^21718519 is an apocalyptic number.

21718519 is a deficient number, since it is larger than the sum of its proper divisors (922489).

21718519 is an equidigital number, since it uses as much as digits as its factorization.

21718519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8865.

The product of its digits is 5040, while the sum is 34.

The square root of 21718519 is about 4660.3131869006. The cubic root of 21718519 is about 279.0037683145.

The spelling of 21718519 in words is "twenty-one million, seven hundred eighteen thousand, five hundred nineteen".