21353842 has 4 divisors (see below), whose sum is σ = 32030766. Its totient is φ = 10676920.

The previous prime is 21353807. The next prime is 21353861. The reversal of 21353842 is 24835312.

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

It can be written as a sum of positive squares in only one way, i.e., 14907321 + 6446521 = 3861^2 + 2539^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21353842.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5338459 + ... + 5338462.

Almost surely, 2^21353842 is an apocalyptic number.

21353842 is a deficient number, since it is larger than the sum of its proper divisors (10676924).

21353842 is a wasteful number, since it uses less digits than its factorization.

21353842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10676923.

The product of its digits is 5760, while the sum is 28.

The square root of 21353842 is about 4621.0217484881. The cubic root of 21353842 is about 277.4333557462.

The spelling of 21353842 in words is "twenty-one million, three hundred fifty-three thousand, eight hundred forty-two".