20921873 has 12 divisors (see below), whose sum is σ = 24675300. Its totient is φ = 17684352.

The previous prime is 20921867. The next prime is 20921897. The reversal of 20921873 is 37812902.

It can be written as a sum of positive squares in 2 ways, for example, as 9443329 + 11478544 = 3073^2 + 3388^2 .

It is not a de Polignac number, because 20921873 - 2⁶ = 20921809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20921843) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 653 + ... + 6501.

It is an arithmetic number, because the mean of its divisors is an integer number (2056275).

Almost surely, 2^20921873 is an apocalyptic number.

It is an amenable number.

20921873 is a deficient number, since it is larger than the sum of its proper divisors (3753427).

20921873 is an equidigital number, since it uses as much as digits as its factorization.

20921873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5936 (or 5929 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20921873 is about 4574.0433972581. The cubic root of 20921873 is about 275.5498552182.

The spelling of 20921873 in words is "twenty million, nine hundred twenty-one thousand, eight hundred seventy-three".