21421318 has 4 divisors (see below), whose sum is σ = 32131980. Its totient is φ = 10710658.

The previous prime is 21421273. The next prime is 21421319. The reversal of 21421318 is 81312412.

It is a happy number.

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

It is a super-3 number, since 3×21421318³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5355328 + ... + 5355331.

It is an arithmetic number, because the mean of its divisors is an integer number (8032995).

Almost surely, 2^21421318 is an apocalyptic number.

21421318 is a deficient number, since it is larger than the sum of its proper divisors (10710662).

21421318 is a wasteful number, since it uses less digits than its factorization.

21421318 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10710661.

The product of its digits is 384, while the sum is 22.

The square root of 21421318 is about 4628.3169727235. The cubic root of 21421318 is about 277.7252690200.

The spelling of 21421318 in words is "twenty-one million, four hundred twenty-one thousand, three hundred eighteen".