21713719 has 4 divisors (see below), whose sum is σ = 21847096. Its totient is φ = 21580344.

The previous prime is 21713707. The next prime is 21713737. The reversal of 21713719 is 91731712.

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 21713719 - 2⁹ = 21713207 is a prime.

It is a super-2 number, since 2×21713719² = 942971185621922, 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 (21713819) 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, 66444 + ... + 66769.

It is an arithmetic number, because the mean of its divisors is an integer number (5461774).

Almost surely, 2^21713719 is an apocalyptic number.

21713719 is a deficient number, since it is larger than the sum of its proper divisors (133377).

21713719 is a wasteful number, since it uses less digits than its factorization.

21713719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133376.

The product of its digits is 2646, while the sum is 31.

The square root of 21713719 is about 4659.7981715950. The cubic root of 21713719 is about 278.9832126348.

It can be divided in two parts, 217137 and 19, that added together give a square (217156 = 466²).

The spelling of 21713719 in words is "twenty-one million, seven hundred thirteen thousand, seven hundred nineteen".