21159705 has 32 divisors (see below), whose sum is σ = 40032000. Its totient is φ = 9338112.

The previous prime is 21159689. The next prime is 21159709. The reversal of 21159705 is 50795112.

It is not a de Polignac number, because 21159705 - 2⁴ = 21159689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21159709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 430 + ... + 6519.

It is an arithmetic number, because the mean of its divisors is an integer number (1251000).

Almost surely, 2^21159705 is an apocalyptic number.

It is an amenable number.

21159705 is a deficient number, since it is larger than the sum of its proper divisors (18872295).

21159705 is a wasteful number, since it uses less digits than its factorization.

21159705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6993.

The product of its (nonzero) digits is 3150, while the sum is 30.

The square root of 21159705 is about 4599.9679346708. The cubic root of 21159705 is about 276.5900394230.

The spelling of 21159705 in words is "twenty-one million, one hundred fifty-nine thousand, seven hundred five".