21309619 has 8 divisors (see below), whose sum is σ = 22613040. Its totient is φ = 20011776.

The previous prime is 21309611. The next prime is 21309623. The reversal of 21309619 is 91690312.

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 21309619 - 2³ = 21309611 is a prime.

It is a super-3 number, since 3×21309619³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21309611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8572 + ... + 10774.

It is an arithmetic number, because the mean of its divisors is an integer number (2826630).

Almost surely, 2^21309619 is an apocalyptic number.

21309619 is a deficient number, since it is larger than the sum of its proper divisors (1303421).

21309619 is a wasteful number, since it uses less digits than its factorization.

21309619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2789.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21309619 is about 4616.2342878151. The cubic root of 21309619 is about 277.2417053857.

The spelling of 21309619 in words is "twenty-one million, three hundred nine thousand, six hundred nineteen".