21438930 has 32 divisors (see below), whose sum is σ = 51585984. Its totient is φ = 5702336.

The previous prime is 21438913. The next prime is 21438931. The reversal of 21438930 is 3983412.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21438931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16069 + ... + 17351.

It is an arithmetic number, because the mean of its divisors is an integer number (1612062).

Almost surely, 2^21438930 is an apocalyptic number.

21438930 is an abundant number, since it is smaller than the sum of its proper divisors (30147054).

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

21438930 is a wasteful number, since it uses less digits than its factorization.

21438930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1850.

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 21438930 is about 4630.2192172725. The cubic root of 21438930 is about 277.8013607830.

The spelling of 21438930 in words is "twenty-one million, four hundred thirty-eight thousand, nine hundred thirty".