21718406 has 16 divisors (see below), whose sum is σ = 34389360. Its totient is φ = 10258560.

The previous prime is 21718391. The next prime is 21718409. The reversal of 21718406 is 60481712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718409) 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, 19250 + ... + 20346.

It is an arithmetic number, because the mean of its divisors is an integer number (2149335).

Almost surely, 2^21718406 is an apocalyptic number.

21718406 is a deficient number, since it is larger than the sum of its proper divisors (12670954).

21718406 is a wasteful number, since it uses less digits than its factorization.

21718406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21718406 is about 4660.3010632362. The cubic root of 21718406 is about 279.0032844344.

The spelling of 21718406 in words is "twenty-one million, seven hundred eighteen thousand, four hundred six".