21307755 has 16 divisors (see below), whose sum is σ = 38962944. Its totient is φ = 9740640.

The previous prime is 21307753. The next prime is 21307771. The reversal of 21307755 is 55770312.

It is not a de Polignac number, because 21307755 - 2¹ = 21307753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21307753) 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 15 ways as a sum of consecutive naturals, for example, 101361 + ... + 101570.

It is an arithmetic number, because the mean of its divisors is an integer number (2435184).

Almost surely, 2^21307755 is an apocalyptic number.

21307755 is a deficient number, since it is larger than the sum of its proper divisors (17655189).

21307755 is a wasteful number, since it uses less digits than its factorization.

21307755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202946.

The product of its (nonzero) digits is 7350, while the sum is 30.

The square root of 21307755 is about 4616.0323872347. The cubic root of 21307755 is about 277.2336214995.

The spelling of 21307755 in words is "twenty-one million, three hundred seven thousand, seven hundred fifty-five".