21003673 has 2 divisors, whose sum is σ = 21003674.
Its totient is φ = 21003672.
The previous prime is 21003667. The next prime is 21003677. The reversal of 21003673 is 37630012.
Adding to 21003673 its reverse (37630012), we get a palindrome (58633685).
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 20903184 + 100489 = 4572^2 + 317^2
It is a cyclic number.
It is not a de Polignac number, because 21003673 - 217 = 20872601 is a prime.
It is not a weakly prime, because it can be changed into another prime (21003677) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501836 + 10501837.
It is an arithmetic number, because the mean of its divisors is an integer number (10501837).
Almost surely, 221003673 is an apocalyptic number.
It is an amenable number.
21003673 is a deficient number, since it is larger than the sum of its proper divisors (1).
21003673 is an equidigital number, since it uses as much as digits as its factorization.
21003673 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 756, while the sum is 22.
The square root of 21003673 is about 4582.9764345892.
The cubic root of 21003673 is about 275.9085016663.
The spelling of 21003673 in words is "twenty-one million, three thousand, six hundred seventy-three".