21013351 has 4 divisors (see below), whose sum is σ = 21147352. Its totient is φ = 20879352.

The previous prime is 21013303. The next prime is 21013357. The reversal of 21013351 is 15331012.

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

It is a cyclic number.

It is not a de Polignac number, because 21013351 - 2²¹ = 18916199 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 (21013357) 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 3 ways as a sum of consecutive naturals, for example, 66765 + ... + 67078.

It is an arithmetic number, because the mean of its divisors is an integer number (5286838).

Almost surely, 2^21013351 is an apocalyptic number.

21013351 is a deficient number, since it is larger than the sum of its proper divisors (134001).

21013351 is a wasteful number, since it uses less digits than its factorization.

21013351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134000.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21013351 is about 4584.0321770249. The cubic root of 21013351 is about 275.9508725484.

Adding to 21013351 its reverse (15331012), we get a palindrome (36344363).

The spelling of 21013351 in words is "twenty-one million, thirteen thousand, three hundred fifty-one".