21051733 has 4 divisors (see below), whose sum is σ = 21260268. Its totient is φ = 20843200.

The previous prime is 21051727. The next prime is 21051743. The reversal of 21051733 is 33715012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9375844 + 11675889 = 3062^2 + 3417^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21051733 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051703) 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, 104116 + ... + 104317.

It is an arithmetic number, because the mean of its divisors is an integer number (5315067).

Almost surely, 2^21051733 is an apocalyptic number.

It is an amenable number.

21051733 is a deficient number, since it is larger than the sum of its proper divisors (208535).

21051733 is a wasteful number, since it uses less digits than its factorization.

21051733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208534.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21051733 is about 4588.2167559957. The cubic root of 21051733 is about 276.1187833249.

Adding to 21051733 its reverse (33715012), we get a palindrome (54766745).

The spelling of 21051733 in words is "twenty-one million, fifty-one thousand, seven hundred thirty-three".