21033331 has 4 divisors (see below), whose sum is σ = 22945464. Its totient is φ = 19121200.

The previous prime is 21033329. The next prime is 21033343. The reversal of 21033331 is 13333012.

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 21033331 - 2¹ = 21033329 is a prime.

It is a super-2 number, since 2×21033331² = 884802025911122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21033371) 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, 956050 + ... + 956071.

It is an arithmetic number, because the mean of its divisors is an integer number (5736366).

Almost surely, 2^21033331 is an apocalyptic number.

21033331 is a deficient number, since it is larger than the sum of its proper divisors (1912133).

21033331 is a wasteful number, since it uses less digits than its factorization.

21033331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1912132.

The product of its (nonzero) digits is 162, while the sum is 16.

The square root of 21033331 is about 4586.2109633117. The cubic root of 21033331 is about 276.0383050875.

Adding to 21033331 its reverse (13333012), we get a palindrome (34366343).

The spelling of 21033331 in words is "twenty-one million, thirty-three thousand, three hundred thirty-one".