21406230 has 72 divisors (see below), whose sum is σ = 59194512. Its totient is φ = 5366016.

The previous prime is 21406207. The next prime is 21406237. The reversal of 21406230 is 3260412.

It is a happy number.

21406230 is a `hidden beast` number, since 2 + 1 + 40 + 623 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406237) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 25599 + ... + 26421.

It is an arithmetic number, because the mean of its divisors is an integer number (822146).

Almost surely, 2^21406230 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21406230, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29597256).

21406230 is an abundant number, since it is smaller than the sum of its proper divisors (37788282).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21406230 is a wasteful number, since it uses less digits than its factorization.

21406230 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870 (or 850 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21406230 is about 4626.6867194570. The cubic root of 21406230 is about 277.6600488959.

Adding to 21406230 its reverse (3260412), we get a palindrome (24666642).

The spelling of 21406230 in words is "twenty-one million, four hundred six thousand, two hundred thirty".