21755449 has 4 divisors (see below), whose sum is σ = 21780864. Its totient is φ = 21730036.

The previous prime is 21755429. The next prime is 21755471. The reversal of 21755449 is 94455712.

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 21755449 - 2¹⁷ = 21624377 is a prime.

It is a super-3 number, since 3×21755449³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21755429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11377 + ... + 13150.

It is an arithmetic number, because the mean of its divisors is an integer number (5445216).

Almost surely, 2^21755449 is an apocalyptic number.

It is an amenable number.

21755449 is a deficient number, since it is larger than the sum of its proper divisors (25415).

21755449 is an equidigital number, since it uses as much as digits as its factorization.

21755449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25414.

The product of its digits is 50400, while the sum is 37.

The square root of 21755449 is about 4664.2736840799. The cubic root of 21755449 is about 279.1618173757.

The spelling of 21755449 in words is "twenty-one million, seven hundred fifty-five thousand, four hundred forty-nine".