21147719 has 4 divisors (see below), whose sum is σ = 21289800. Its totient is φ = 21005640.

The previous prime is 21147713. The next prime is 21147727. The reversal of 21147719 is 91774112.

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 21147719 - 2¹² = 21143623 is a prime.

It is a super-4 number, since 4×21147719⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21147713) 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, 70817 + ... + 71114.

It is an arithmetic number, because the mean of its divisors is an integer number (5322450).

Almost surely, 2^21147719 is an apocalyptic number.

21147719 is a deficient number, since it is larger than the sum of its proper divisors (142081).

21147719 is a wasteful number, since it uses less digits than its factorization.

21147719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142080.

The product of its digits is 3528, while the sum is 32.

The square root of 21147719 is about 4598.6649149509. The cubic root of 21147719 is about 276.5378043788.

The spelling of 21147719 in words is "twenty-one million, one hundred forty-seven thousand, seven hundred nineteen".