21161648 has 40 divisors (see below), whose sum is σ = 43189200. Its totient is φ = 10029824.

The previous prime is 21161641. The next prime is 21161653. The reversal of 21161648 is 84616112.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a self number, because there is not a number n which added to its sum of digits gives 21161648.

It is not an unprimeable number, because it can be changed into a prime (21161641) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 26990 + ... + 27762.

It is an arithmetic number, because the mean of its divisors is an integer number (1079730).

Almost surely, 2^21161648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21161648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21594600).

21161648 is an abundant number, since it is smaller than the sum of its proper divisors (22027552).

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

21161648 is a wasteful number, since it uses less digits than its factorization.

21161648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869 (or 863 counting only the distinct ones).

The product of its digits is 2304, while the sum is 29.

The square root of 21161648 is about 4600.1791269471. The cubic root of 21161648 is about 276.5985051680.

The spelling of 21161648 in words is "twenty-one million, one hundred sixty-one thousand, six hundred forty-eight".