21515003 has 2 divisors, whose sum is σ = 21515004. Its totient is φ = 21515002.

The previous prime is 21514993. The next prime is 21515009. The reversal of 21515003 is 30051512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21515003 - 2¹⁰ = 21513979 is a prime.

It is not a weakly prime, because it can be changed into another prime (21515009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757501 + 10757502.

It is an arithmetic number, because the mean of its divisors is an integer number (10757502).

Almost surely, 2^21515003 is an apocalyptic number.

21515003 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515003 is an equidigital number, since it uses as much as digits as its factorization.

21515003 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21515003 is about 4638.4267807092. The cubic root of 21515003 is about 278.1295524736.

Adding to 21515003 its reverse (30051512), we get a palindrome (51566515).

The spelling of 21515003 in words is "twenty-one million, five hundred fifteen thousand, three".