21757960 has 96 divisors (see below), whose sum is σ = 60390360. Its totient is φ = 7010304.

The previous prime is 21757951. The next prime is 21757969. The reversal of 21757960 is 6975712.

It is an interprime number because it is at equal distance from previous prime (21757951) and next prime (21757969).

It can be written as a sum of positive squares in 4 ways, for example, as 17522596 + 4235364 = 4186^2 + 2058^2 .

It is not an unprimeable number, because it can be changed into a prime (21757969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32994 + ... + 33646.

Almost surely, 2^21757960 is an apocalyptic number.

21757960 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 21757960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30195180).

21757960 is an abundant number, since it is smaller than the sum of its proper divisors (38632400).

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

21757960 is a wasteful number, since it uses less digits than its factorization.

21757960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695 (or 684 counting only the distinct ones).

The product of its (nonzero) digits is 26460, while the sum is 37.

The square root of 21757960 is about 4664.5428500551. The cubic root of 21757960 is about 279.1725571886.

The spelling of 21757960 in words is "twenty-one million, seven hundred fifty-seven thousand, nine hundred sixty".