21809792 has 16 divisors (see below), whose sum is σ = 43449450. Its totient is φ = 10904832.

The previous prime is 21809789. The next prime is 21809863. The reversal of 21809792 is 29790812.

It can be written as a sum of positive squares in only one way, i.e., 19571776 + 2238016 = 4424^2 + 1496^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85067 + ... + 85322.

Almost surely, 2^21809792 is an apocalyptic number.

It is an amenable number.

21809792 is a deficient number, since it is larger than the sum of its proper divisors (21639658).

21809792 is an equidigital number, since it uses as much as digits as its factorization.

21809792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170403 (or 170391 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 21809792 is about 4670.0955022355. The cubic root of 21809792 is about 279.3940638146.

The spelling of 21809792 in words is "twenty-one million, eight hundred nine thousand, seven hundred ninety-two".