21775760 has 40 divisors (see below), whose sum is σ = 50856120. Its totient is φ = 8671232.

The previous prime is 21775753. The next prime is 21775763. The reversal of 21775760 is 6757712.

It can be written as a sum of positive squares in 4 ways, for example, as 1597696 + 20178064 = 1264^2 + 4492^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 21775760.

It is not an unprimeable number, because it can be changed into a prime (21775763) 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, 22976 + ... + 23904.

It is an arithmetic number, because the mean of its divisors is an integer number (1271403).

Almost surely, 2^21775760 is an apocalyptic number.

21775760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21775760 is an abundant number, since it is smaller than the sum of its proper divisors (29080360).

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

21775760 is a wasteful number, since it uses less digits than its factorization.

21775760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235 (or 1229 counting only the distinct ones).

The product of its (nonzero) digits is 20580, while the sum is 35.

The square root of 21775760 is about 4666.4504711826. The cubic root of 21775760 is about 279.2486659940.

The spelling of 21775760 in words is "twenty-one million, seven hundred seventy-five thousand, seven hundred sixty".