21220549 has 8 divisors (see below), whose sum is σ = 25528640. Its totient is φ = 17231616.

The previous prime is 21220531. The next prime is 21220583. The reversal of 21220549 is 94502212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21220549 - 2¹⁵ = 21187781 is a prime.

It is a super-2 number, since 2×21220549² = 900623399722802, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220349) 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, 79644 + ... + 79909.

It is an arithmetic number, because the mean of its divisors is an integer number (3191080).

Almost surely, 2^21220549 is an apocalyptic number.

It is an amenable number.

21220549 is a deficient number, since it is larger than the sum of its proper divisors (4308091).

21220549 is a wasteful number, since it uses less digits than its factorization.

21220549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159579.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21220549 is about 4606.5767116157. The cubic root of 21220549 is about 276.8548940894.

The spelling of 21220549 in words is "twenty-one million, two hundred twenty thousand, five hundred forty-nine".