21755745 has 24 divisors (see below), whose sum is σ = 41139072.
Its totient is φ = 10548000.
The previous prime is 21755717. The next prime is 21755761. The reversal of 21755745 is 54755712.
It is not a de Polignac number, because 21755745 - 212 = 21751649 is a prime.
It is a Curzon number.
It is an unprimeable number.
It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21481 + ... + 22470.
It is an arithmetic number, because the mean of its divisors is an integer number (1714128).
Almost surely, 221755745 is an apocalyptic number.
It is an amenable number.
21755745 is a deficient number, since it is larger than the sum of its proper divisors (19383327).
21755745 is a wasteful number, since it uses less digits than its factorization.
21755745 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 43973 (or 43970 counting only the distinct ones).
The product of its digits is 49000, while the sum is 36.
The square root of 21755745 is about 4664.3054145285.
The cubic root of 21755745 is about 279.1630834420.
It can be divided in two parts, 21755 and 745, that added together give a square (22500 = 1502).
The spelling of 21755745 in words is "twenty-one million, seven hundred fifty-five thousand, seven hundred forty-five".