21545549 has 8 divisors (see below), whose sum is σ = 22636800. Its totient is φ = 20467216.

The previous prime is 21545509. The next prime is 21545551. The reversal of 21545549 is 94554512.

It is a happy number.

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 21545549 - 2¹² = 21541453 is a prime.

It is a super-2 number, since 2×21545549² = 928421363422802, 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 (21545509) 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, 284 + ... + 6570.

It is an arithmetic number, because the mean of its divisors is an integer number (2829600).

Almost surely, 2^21545549 is an apocalyptic number.

It is an amenable number.

21545549 is a deficient number, since it is larger than the sum of its proper divisors (1091251).

21545549 is a wasteful number, since it uses less digits than its factorization.

21545549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6459.

The product of its digits is 36000, while the sum is 35.

The square root of 21545549 is about 4641.7183240692. The cubic root of 21545549 is about 278.2611153626.

The spelling of 21545549 in words is "twenty-one million, five hundred forty-five thousand, five hundred forty-nine".