21551149 has 4 divisors (see below), whose sum is σ = 22685440. Its totient is φ = 20416860.

The previous prime is 21551143. The next prime is 21551171. The reversal of 21551149 is 94115512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21551149 - 2⁹ = 21550637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21551143) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 567117 + ... + 567154.

It is an arithmetic number, because the mean of its divisors is an integer number (5671360).

Almost surely, 2^21551149 is an apocalyptic number.

It is an amenable number.

21551149 is a deficient number, since it is larger than the sum of its proper divisors (1134291).

21551149 is a wasteful number, since it uses less digits than its factorization.

21551149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1134290.

The product of its digits is 1800, while the sum is 28.

The square root of 21551149 is about 4642.3215097621. The cubic root of 21551149 is about 278.2852213045.

The spelling of 21551149 in words is "twenty-one million, five hundred fifty-one thousand, one hundred forty-nine".