21518719 has 8 divisors (see below), whose sum is σ = 23401008. Its totient is φ = 19704960.

The previous prime is 21518713. The next prime is 21518723. The reversal of 21518719 is 91781512.

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 21518719 - 2³ = 21518711 is a prime.

It is a super-2 number, since 2×21518719² = 926110534801922, 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 (21518711) 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, 16477 + ... + 17734.

It is an arithmetic number, because the mean of its divisors is an integer number (2925126).

Almost surely, 2^21518719 is an apocalyptic number.

21518719 is a deficient number, since it is larger than the sum of its proper divisors (1882289).

21518719 is a wasteful number, since it uses less digits than its factorization.

21518719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34265.

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

The square root of 21518719 is about 4638.8273302635. The cubic root of 21518719 is about 278.1455640899.

The spelling of 21518719 in words is "twenty-one million, five hundred eighteen thousand, seven hundred nineteen".