21730580 has 12 divisors (see below), whose sum is σ = 45634260. Its totient is φ = 8692224.

The previous prime is 21730559. The next prime is 21730637. The reversal of 21730580 is 8503712.

It can be written as a sum of positive squares in 2 ways, for example, as 13630864 + 8099716 = 3692^2 + 2846^2 .

It is a super-3 number, since 3×21730580³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 543245 + ... + 543284.

It is an arithmetic number, because the mean of its divisors is an integer number (3802855).

Almost surely, 2^21730580 is an apocalyptic number.

21730580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21730580 is an abundant number, since it is smaller than the sum of its proper divisors (23903680).

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

21730580 is a wasteful number, since it uses less digits than its factorization.

21730580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086538 (or 1086536 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21730580 is about 4661.6070190440. The cubic root of 21730580 is about 279.0554053795.

The spelling of 21730580 in words is "twenty-one million, seven hundred thirty thousand, five hundred eighty".