21018073 has 2 divisors, whose sum is σ = 21018074. Its totient is φ = 21018072.

The previous prime is 21018043. The next prime is 21018079. The reversal of 21018073 is 37081012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15272464 + 5745609 = 3908^2 + 2397^2 .

It is a cyclic number.

It is not a de Polignac number, because 21018073 - 2¹⁷ = 20887001 is a prime.

It is not a weakly prime, because it can be changed into another prime (21018079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509036 + 10509037.

It is an arithmetic number, because the mean of its divisors is an integer number (10509037).

Almost surely, 2^21018073 is an apocalyptic number.

It is an amenable number.

21018073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21018073 is an equidigital number, since it uses as much as digits as its factorization.

21018073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21018073 is about 4584.5471968342. The cubic root of 21018073 is about 275.9715410340.

Adding to 21018073 its reverse (37081012), we get a palindrome (58099085).

The spelling of 21018073 in words is "twenty-one million, eighteen thousand, seventy-three".