21718006 has 4 divisors (see below), whose sum is σ = 32577012. Its totient is φ = 10859002.

The previous prime is 21717989. The next prime is 21718033. The reversal of 21718006 is 60081712.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5429500 + ... + 5429503.

It is an arithmetic number, because the mean of its divisors is an integer number (8144253).

Almost surely, 2^21718006 is an apocalyptic number.

21718006 is a deficient number, since it is larger than the sum of its proper divisors (10859006).

21718006 is a wasteful number, since it uses less digits than its factorization.

21718006 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10859005.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21718006 is about 4660.2581473562. The cubic root of 21718006 is about 279.0015715708.

Adding to 21718006 its reverse (60081712), we get a palindrome (81799718).

The spelling of 21718006 in words is "twenty-one million, seven hundred eighteen thousand, six".