21719009 has 8 divisors (see below), whose sum is σ = 23425920. Its totient is φ = 20017296.

The previous prime is 21718997. The next prime is 21719023. The reversal of 21719009 is 90091712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21719009 - 2⁴ = 21718993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21719069) 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, 15704 + ... + 17030.

It is an arithmetic number, because the mean of its divisors is an integer number (2928240).

Almost surely, 2^21719009 is an apocalyptic number.

It is an amenable number.

21719009 is a deficient number, since it is larger than the sum of its proper divisors (1706911).

21719009 is a wasteful number, since it uses less digits than its factorization.

21719009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2599.

The product of its (nonzero) digits is 1134, while the sum is 29.

The square root of 21719009 is about 4660.3657581782. The cubic root of 21719009 is about 279.0058665365.

The spelling of 21719009 in words is "twenty-one million, seven hundred nineteen thousand, nine".