21011873 has 2 divisors, whose sum is σ = 21011874. Its totient is φ = 21011872.

The previous prime is 21011869. The next prime is 21011917. The reversal of 21011873 is 37811012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17447329 + 3564544 = 4177^2 + 1888^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011873 - 2² = 21011869 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505936 + 10505937.

It is an arithmetic number, because the mean of its divisors is an integer number (10505937).

Almost surely, 2^21011873 is an apocalyptic number.

It is an amenable number.

21011873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011873 is an equidigital number, since it uses as much as digits as its factorization.

21011873 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 23.

The square root of 21011873 is about 4583.8709624072. The cubic root of 21011873 is about 275.9444026149.

Adding to 21011873 its reverse (37811012), we get a palindrome (58822885).

The spelling of 21011873 in words is "twenty-one million, eleven thousand, eight hundred seventy-three".