21516719 has 4 divisors (see below), whose sum is σ = 24590544. Its totient is φ = 18442896.

The previous prime is 21516689. The next prime is 21516731. The reversal of 21516719 is 91761512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21516719 is a prime.

It is a super-2 number, since 2×21516719² = 925938393049922, 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 (21516739) 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, 1536902 + ... + 1536915.

It is an arithmetic number, because the mean of its divisors is an integer number (6147636).

Almost surely, 2^21516719 is an apocalyptic number.

21516719 is a deficient number, since it is larger than the sum of its proper divisors (3073825).

21516719 is an equidigital number, since it uses as much as digits as its factorization.

21516719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3073824.

The product of its digits is 3780, while the sum is 32.

The square root of 21516719 is about 4638.6117535314. The cubic root of 21516719 is about 278.1369466568.

The spelling of 21516719 in words is "twenty-one million, five hundred sixteen thousand, seven hundred nineteen".