21218414 has 16 divisors (see below), whose sum is σ = 38514528. Its totient is φ = 8558592.

The previous prime is 21218413. The next prime is 21218419. The reversal of 21218414 is 41481212.

It is a self number, because there is not a number n which added to its sum of digits gives 21218414.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21218413) 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, 44339 + ... + 44814.

It is an arithmetic number, because the mean of its divisors is an integer number (2407158).

Almost surely, 2^21218414 is an apocalyptic number.

21218414 is a deficient number, since it is larger than the sum of its proper divisors (17296114).

21218414 is a wasteful number, since it uses less digits than its factorization.

21218414 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89179.

The product of its digits is 512, while the sum is 23.

The square root of 21218414 is about 4606.3449718839. The cubic root of 21218414 is about 276.8456089852.

Adding to 21218414 its reverse (41481212), we get a palindrome (62699626).

The spelling of 21218414 in words is "twenty-one million, two hundred eighteen thousand, four hundred fourteen".