21549649 has 8 divisors (see below), whose sum is σ = 23598720. Its totient is φ = 19515600.

The previous prime is 21549637. The next prime is 21549677. The reversal of 21549649 is 94694512.

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 21549649 - 2²¹ = 19452497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21549049) 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, 634 + ... + 6595.

It is an arithmetic number, because the mean of its divisors is an integer number (2949840).

Almost surely, 2^21549649 is an apocalyptic number.

It is an amenable number.

21549649 is a deficient number, since it is larger than the sum of its proper divisors (2049071).

21549649 is a wasteful number, since it uses less digits than its factorization.

21549649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7511.

The product of its digits is 77760, while the sum is 40.

The square root of 21549649 is about 4642.1599498509. The cubic root of 21549649 is about 278.2787647653.

The spelling of 21549649 in words is "twenty-one million, five hundred forty-nine thousand, six hundred forty-nine".