21406330 has 32 divisors (see below), whose sum is σ = 43867008. Its totient is φ = 7444800.

The previous prime is 21406279. The next prime is 21406339. The reversal of 21406330 is 3360412.

It is a junction number, because it is equal to n+sod(n) for n = 21406298 and 21406307.

It is not an unprimeable number, because it can be changed into a prime (21406339) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1701 + ... + 6760.

It is an arithmetic number, because the mean of its divisors is an integer number (1370844).

Almost surely, 2^21406330 is an apocalyptic number.

21406330 is an abundant number, since it is smaller than the sum of its proper divisors (22460678).

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

21406330 is a wasteful number, since it uses less digits than its factorization.

21406330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8502.

The product of its (nonzero) digits is 432, while the sum is 19.

The square root of 21406330 is about 4626.6975263140. The cubic root of 21406330 is about 277.6604812617.

Adding to 21406330 its reverse (3360412), we get a palindrome (24766742).

It can be divided in two parts, 21406 and 330, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21406330 in words is "twenty-one million, four hundred six thousand, three hundred thirty".