21148816 has 40 divisors (see below), whose sum is σ = 46731384. Its totient is φ = 9185280.

The previous prime is 21148811. The next prime is 21148823. The reversal of 21148816 is 61884112.

It can be written as a sum of positive squares in 4 ways, for example, as 25600 + 21123216 = 160^2 + 4596^2 .

It is not an unprimeable number, because it can be changed into a prime (21148811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 546 + ... + 6526.

Almost surely, 2^21148816 is an apocalyptic number.

21148816 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21148816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23365692).

21148816 is an abundant number, since it is smaller than the sum of its proper divisors (25582568).

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

21148816 is a wasteful number, since it uses less digits than its factorization.

21148816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6019 (or 6013 counting only the distinct ones).

The product of its digits is 3072, while the sum is 31.

The square root of 21148816 is about 4598.7841871521. The cubic root of 21148816 is about 276.5425859303.

The spelling of 21148816 in words is "twenty-one million, one hundred forty-eight thousand, eight hundred sixteen".