21549380 has 12 divisors (see below), whose sum is σ = 45253740. Its totient is φ = 8619744.

The previous prime is 21549301. The next prime is 21549389. The reversal of 21549380 is 8394512.

It can be written as a sum of positive squares in 2 ways, for example, as 17156164 + 4393216 = 4142^2 + 2096^2 .

It is a super-3 number, since 3×21549380³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21549389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 538715 + ... + 538754.

It is an arithmetic number, because the mean of its divisors is an integer number (3771145).

Almost surely, 2^21549380 is an apocalyptic number.

21549380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21549380 is an abundant number, since it is smaller than the sum of its proper divisors (23704360).

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

21549380 is a wasteful number, since it uses less digits than its factorization.

21549380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1077478 (or 1077476 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 21549380 is about 4642.1309761789. The cubic root of 21549380 is about 278.2776068609.

The spelling of 21549380 in words is "twenty-one million, five hundred forty-nine thousand, three hundred eighty".