21251873 has 2 divisors, whose sum is σ = 21251874. Its totient is φ = 21251872.

The previous prime is 21251863. The next prime is 21251897. The reversal of 21251873 is 37815212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20857489 + 394384 = 4567^2 + 628^2 .

It is a cyclic number.

It is not a de Polignac number, because 21251873 - 2⁸ = 21251617 is a prime.

It is not a weakly prime, because it can be changed into another prime (21251803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625936 + 10625937.

It is an arithmetic number, because the mean of its divisors is an integer number (10625937).

Almost surely, 2^21251873 is an apocalyptic number.

It is an amenable number.

21251873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251873 is an equidigital number, since it uses as much as digits as its factorization.

21251873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 29.

The square root of 21251873 is about 4609.9753795438. The cubic root of 21251873 is about 276.9910504652.

The spelling of 21251873 in words is "twenty-one million, two hundred fifty-one thousand, eight hundred seventy-three".