21755751 has 8 divisors (see below), whose sum is σ = 29069184. Its totient is φ = 14473080.

The previous prime is 21755717. The next prime is 21755761. The reversal of 21755751 is 15755712.

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

It is not a de Polignac number, because 21755751 - 2¹⁵ = 21722983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5985 + ... + 8906.

It is an arithmetic number, because the mean of its divisors is an integer number (3633648).

Almost surely, 2^21755751 is an apocalyptic number.

21755751 is a deficient number, since it is larger than the sum of its proper divisors (7313433).

21755751 is a wasteful number, since it uses less digits than its factorization.

21755751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15381.

The product of its digits is 12250, while the sum is 33.

The square root of 21755751 is about 4664.3060577111. The cubic root of 21755751 is about 279.1631091054.

The spelling of 21755751 in words is "twenty-one million, seven hundred fifty-five thousand, seven hundred fifty-one".