21437873 has 8 divisors (see below), whose sum is σ = 22408680. Its totient is φ = 20482560.

The previous prime is 21437869. The next prime is 21437881. The reversal of 21437873 is 37873412.

It can be written as a sum of positive squares in 4 ways, for example, as 6822544 + 14615329 = 2612^2 + 3823^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21437873 - 2² = 21437869 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21437803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 998 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (2801085).

Almost surely, 2^21437873 is an apocalyptic number.

It is an amenable number.

21437873 is a deficient number, since it is larger than the sum of its proper divisors (970807).

21437873 is an equidigital number, since it uses as much as digits as its factorization.

21437873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7747.

The product of its digits is 28224, while the sum is 35.

The square root of 21437873 is about 4630.1050744017. The cubic root of 21437873 is about 277.7967952432.

The spelling of 21437873 in words is "twenty-one million, four hundred thirty-seven thousand, eight hundred seventy-three".