21549057 has 8 divisors (see below), whose sum is σ = 29016960. Its totient is φ = 14223600.

The previous prime is 21549049. The next prime is 21549071. The reversal of 21549057 is 75094512.

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

It is not a de Polignac number, because 21549057 - 2³ = 21549049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21549257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35257 + ... + 35862.

It is an arithmetic number, because the mean of its divisors is an integer number (3627120).

Almost surely, 2^21549057 is an apocalyptic number.

It is an amenable number.

21549057 is a deficient number, since it is larger than the sum of its proper divisors (7467903).

21549057 is a wasteful number, since it uses less digits than its factorization.

21549057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71223.

The product of its (nonzero) digits is 12600, while the sum is 33.

The square root of 21549057 is about 4642.0961859918. The cubic root of 21549057 is about 278.2762165020.

It can be divided in two parts, 2154 and 9057, that added together give a palindrome (11211).

The spelling of 21549057 in words is "twenty-one million, five hundred forty-nine thousand, fifty-seven".