21013331 has 4 divisors (see below), whose sum is σ = 21024672. Its totient is φ = 21001992.

The previous prime is 21013303. The next prime is 21013357. The reversal of 21013331 is 13331012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21013331 - 2¹⁰ = 21012307 is a prime.

It is a super-2 number, since 2×21013331² = 883120159431122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013301) 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, 2171 + ... + 6836.

It is an arithmetic number, because the mean of its divisors is an integer number (5256168).

Almost surely, 2^21013331 is an apocalyptic number.

21013331 is a deficient number, since it is larger than the sum of its proper divisors (11341).

21013331 is an equidigital number, since it uses as much as digits as its factorization.

21013331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11340.

The product of its (nonzero) digits is 54, while the sum is 14.

The square root of 21013331 is about 4584.0299955389. The cubic root of 21013331 is about 275.9507850006.

Adding to 21013331 its reverse (13331012), we get a palindrome (34344343).

The spelling of 21013331 in words is "twenty-one million, thirteen thousand, three hundred thirty-one".