21723619 has 8 divisors (see below), whose sum is σ = 22012560. Its totient is φ = 21436896.

The previous prime is 21723589. The next prime is 21723641. The reversal of 21723619 is 91632712.

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 21723619 - 2¹⁹ = 21199331 is a prime.

It is a super-2 number, since 2×21723619² = 943831244914322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21723649) 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, 27717 + ... + 28489.

It is an arithmetic number, because the mean of its divisors is an integer number (2751570).

Almost surely, 2^21723619 is an apocalyptic number.

21723619 is a deficient number, since it is larger than the sum of its proper divisors (288941).

21723619 is a wasteful number, since it uses less digits than its factorization.

21723619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1109.

The product of its digits is 4536, while the sum is 31.

The square root of 21723619 is about 4660.8603283085. The cubic root of 21723619 is about 279.0256054060.

The spelling of 21723619 in words is "twenty-one million, seven hundred twenty-three thousand, six hundred nineteen".