21353438 has 4 divisors (see below), whose sum is σ = 32030160. Its totient is φ = 10676718.

The previous prime is 21353419. The next prime is 21353441. The reversal of 21353438 is 83435312.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21353438.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5338358 + ... + 5338361.

It is an arithmetic number, because the mean of its divisors is an integer number (8007540).

Almost surely, 2^21353438 is an apocalyptic number.

21353438 is a deficient number, since it is larger than the sum of its proper divisors (10676722).

21353438 is a wasteful number, since it uses less digits than its factorization.

21353438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10676721.

The product of its digits is 8640, while the sum is 29.

The square root of 21353438 is about 4620.9780350051. The cubic root of 21353438 is about 277.4316061191.

The spelling of 21353438 in words is "twenty-one million, three hundred fifty-three thousand, four hundred thirty-eight".