21549740 has 24 divisors (see below), whose sum is σ = 45384192. Its totient is φ = 8595200.

The previous prime is 21549719. The next prime is 21549757. The reversal of 21549740 is 4794512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21549697 and 21549706.

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 7 ways as a sum of consecutive naturals, for example, 6677 + ... + 9363.

It is an arithmetic number, because the mean of its divisors is an integer number (1891008).

Almost surely, 2^21549740 is an apocalyptic number.

21549740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21549740 is an abundant number, since it is smaller than the sum of its proper divisors (23834452).

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

21549740 is a wasteful number, since it uses less digits than its factorization.

21549740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3097 (or 3095 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21549740 is about 4642.1697513124. The cubic root of 21549740 is about 278.2791564706.

The spelling of 21549740 in words is "twenty-one million, five hundred forty-nine thousand, seven hundred forty".