21791760 has 160 divisors (see below), whose sum is σ = 72852480. Its totient is φ = 5376000.

The previous prime is 21791753. The next prime is 21791761. The reversal of 21791760 is 6719712.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21791761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 215710 + ... + 215810.

It is an arithmetic number, because the mean of its divisors is an integer number (455328).

Almost surely, 2^21791760 is an apocalyptic number.

21791760 is a gapful number since it is divisible by the number (20) 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 21791760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36426240).

21791760 is an abundant number, since it is smaller than the sum of its proper divisors (51060720).

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

21791760 is a wasteful number, since it uses less digits than its factorization.

21791760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 171 counting only the distinct ones).

The product of its (nonzero) digits is 5292, while the sum is 33.

The square root of 21791760 is about 4668.1645215224. The cubic root of 21791760 is about 279.3170430151.

The spelling of 21791760 in words is "twenty-one million, seven hundred ninety-one thousand, seven hundred sixty".