21342405 has 64 divisors (see below), whose sum is σ = 41564160. Its totient is φ = 9144576.

The previous prime is 21342383. The next prime is 21342407. The reversal of 21342405 is 50424312.

It is not a de Polignac number, because 21342405 - 2⁶ = 21342341 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21342407) 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 63 ways as a sum of consecutive naturals, for example, 130854 + ... + 131016.

It is an arithmetic number, because the mean of its divisors is an integer number (649440).

Almost surely, 2^21342405 is an apocalyptic number.

It is an amenable number.

21342405 is a deficient number, since it is larger than the sum of its proper divisors (20221755).

21342405 is a wasteful number, since it uses less digits than its factorization.

21342405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21342405 is about 4619.7840858638. The cubic root of 21342405 is about 277.3838163090.

Adding to 21342405 its reverse (50424312), we get a palindrome (71766717).

The spelling of 21342405 in words is "twenty-one million, three hundred forty-two thousand, four hundred five".