21438819 has 12 divisors (see below), whose sum is σ = 32789016. Its totient is φ = 13451712.

The previous prime is 21438793. The next prime is 21438827. The reversal of 21438819 is 91883412.

It is not a de Polignac number, because 21438819 - 2⁵ = 21438787 is a prime.

It is a super-2 number, since 2×21438819² = 919245920229522, which contains 22 as substring.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21438839) 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 11 ways as a sum of consecutive naturals, for example, 69909 + ... + 70214.

It is an arithmetic number, because the mean of its divisors is an integer number (2732418).

Almost surely, 2^21438819 is an apocalyptic number.

21438819 is a deficient number, since it is larger than the sum of its proper divisors (11350197).

21438819 is a wasteful number, since it uses less digits than its factorization.

21438819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140146 (or 140143 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 21438819 is about 4630.2072307835. The cubic root of 21438819 is about 277.8008813435.

The spelling of 21438819 in words is "twenty-one million, four hundred thirty-eight thousand, eight hundred nineteen".