21648018 has 16 divisors (see below), whose sum is σ = 49481280. Its totient is φ = 6185136.

The previous prime is 21648001. The next prime is 21648047. The reversal of 21648018 is 81084612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 257673 + ... + 257756.

It is an arithmetic number, because the mean of its divisors is an integer number (3092580).

Almost surely, 2^21648018 is an apocalyptic number.

21648018 is an abundant number, since it is smaller than the sum of its proper divisors (27833262).

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

21648018 is a wasteful number, since it uses less digits than its factorization.

21648018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515441.

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 21648018 is about 4652.7430618937. The cubic root of 21648018 is about 278.7015474781.

It can be divided in two parts, 2 and 1648018, that added together give a triangular number (1648020 = T₁₈₁₅).

The spelling of 21648018 in words is "twenty-one million, six hundred forty-eight thousand, eighteen".