21042311 has 4 divisors (see below), whose sum is σ = 22280112. Its totient is φ = 19804512.

The previous prime is 21042293. The next prime is 21042317. The reversal of 21042311 is 11324012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042317) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 618875 + ... + 618908.

It is an arithmetic number, because the mean of its divisors is an integer number (5570028).

Almost surely, 2^21042311 is an apocalyptic number.

21042311 is a deficient number, since it is larger than the sum of its proper divisors (1237801).

21042311 is a wasteful number, since it uses less digits than its factorization.

21042311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237800.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21042311 is about 4587.1898805260. The cubic root of 21042311 is about 276.0775835592.

Adding to 21042311 its reverse (11324012), we get a palindrome (32366323).

The spelling of 21042311 in words is "twenty-one million, forty-two thousand, three hundred eleven".