21424039 has 16 divisors (see below), whose sum is σ = 27758080. Its totient is φ = 16057440.

The previous prime is 21424027. The next prime is 21424049. The reversal of 21424039 is 93042412.

It is not a de Polignac number, because 21424039 - 2⁹ = 21423527 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424049) 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, 4467 + ... + 7924.

It is an arithmetic number, because the mean of its divisors is an integer number (1734880).

Almost surely, 2^21424039 is an apocalyptic number.

21424039 is a deficient number, since it is larger than the sum of its proper divisors (6334041).

21424039 is a wasteful number, since it uses less digits than its factorization.

21424039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12430.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21424039 is about 4628.6109147346. The cubic root of 21424039 is about 277.7370276874.

It can be divided in two parts, 2142403 and 9, that added together give a palindrome (2142412).

The spelling of 21424039 in words is "twenty-one million, four hundred twenty-four thousand, thirty-nine".