21690448 has 20 divisors (see below), whose sum is σ = 45258388. Its totient is φ = 10010880.

The previous prime is 21690413. The next prime is 21690451. The reversal of 21690448 is 84409612.

It can be written as a sum of positive squares in 2 ways, for example, as 5626384 + 16064064 = 2372^2 + 4008^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51933 + ... + 52348.

Almost surely, 2^21690448 is an apocalyptic number.

It is an amenable number.

21690448 is an abundant number, since it is smaller than the sum of its proper divisors (23567940).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21690448 is a wasteful number, since it uses less digits than its factorization.

21690448 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104302 (or 104296 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 21690448 is about 4657.3005056578. The cubic root of 21690448 is about 278.8835131622.

The spelling of 21690448 in words is "twenty-one million, six hundred ninety thousand, four hundred forty-eight".