21739305 has 16 divisors (see below), whose sum is σ = 39752064. Its totient is φ = 9937920.

The previous prime is 21739303. The next prime is 21739309. The reversal of 21739305 is 50393712.

It is not a de Polignac number, because 21739305 - 2¹ = 21739303 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21739303) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103416 + ... + 103625.

It is an arithmetic number, because the mean of its divisors is an integer number (2484504).

Almost surely, 2^21739305 is an apocalyptic number.

It is an amenable number.

21739305 is a deficient number, since it is larger than the sum of its proper divisors (18012759).

21739305 is a wasteful number, since it uses less digits than its factorization.

21739305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207056.

The product of its (nonzero) digits is 5670, while the sum is 30.

The square root of 21739305 is about 4662.5427611980. The cubic root of 21739305 is about 279.0927480341.

The spelling of 21739305 in words is "twenty-one million, seven hundred thirty-nine thousand, three hundred five".