21117719 has 4 divisors (see below), whose sum is σ = 24134544. Its totient is φ = 18100896.

The previous prime is 21117709. The next prime is 21117737. The reversal of 21117719 is 91771112.

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

It is a cyclic number.

It is not a de Polignac number, because 21117719 - 2⁸ = 21117463 is a prime.

It is a super-2 number, since 2×21117719² = 891916111525922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21117691 and 21117700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117709) 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, 1508402 + ... + 1508415.

It is an arithmetic number, because the mean of its divisors is an integer number (6033636).

Almost surely, 2^21117719 is an apocalyptic number.

21117719 is a deficient number, since it is larger than the sum of its proper divisors (3016825).

21117719 is an equidigital number, since it uses as much as digits as its factorization.

21117719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3016824.

The product of its digits is 882, while the sum is 29.

The square root of 21117719 is about 4595.4019410711. The cubic root of 21117719 is about 276.4069776582.

The spelling of 21117719 in words is "twenty-one million, one hundred seventeen thousand, seven hundred nineteen".