21520133 has 2 divisors, whose sum is σ = 21520134. Its totient is φ = 21520132.

The previous prime is 21520091. The next prime is 21520139. The reversal of 21520133 is 33102512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20775364 + 744769 = 4558^2 + 863^2 .

It is a cyclic number.

It is not a de Polignac number, because 21520133 - 2⁶ = 21520069 is a prime.

It is a super-2 number, since 2×21520133² = 926232248675378, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21520139) 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 as a sum of consecutive naturals, namely, 10760066 + 10760067.

It is an arithmetic number, because the mean of its divisors is an integer number (10760067).

Almost surely, 2^21520133 is an apocalyptic number.

It is an amenable number.

21520133 is a deficient number, since it is larger than the sum of its proper divisors (1).

21520133 is an equidigital number, since it uses as much as digits as its factorization.

21520133 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21520133 is about 4638.9797369680. The cubic root of 21520133 is about 278.1516562929.

Adding to 21520133 its reverse (33102512), we get a palindrome (54622645).

The spelling of 21520133 in words is "twenty-one million, five hundred twenty thousand, one hundred thirty-three".