21520003 has 2 divisors, whose sum is σ = 21520004. Its totient is φ = 21520002.

The previous prime is 21519929. The next prime is 21520013. The reversal of 21520003 is 30002512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21520003 - 2¹³ = 21511811 is a prime.

It is a super-2 number, since 2×21520003² = 926221058240018, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21520013) 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, 10760001 + 10760002.

It is an arithmetic number, because the mean of its divisors is an integer number (10760002).

Almost surely, 2^21520003 is an apocalyptic number.

21520003 is a deficient number, since it is larger than the sum of its proper divisors (1).

21520003 is an equidigital number, since it uses as much as digits as its factorization.

21520003 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 13.

The square root of 21520003 is about 4638.9657252452. The cubic root of 21520003 is about 278.1510962005.

Adding to 21520003 its reverse (30002512), we get a palindrome (51522515).

The spelling of 21520003 in words is "twenty-one million, five hundred twenty thousand, three".