21234505 has 8 divisors (see below), whose sum is σ = 25539912. Its totient is φ = 16948608.

The previous prime is 21234487. The next prime is 21234509. The reversal of 21234505 is 50543212.

It can be written as a sum of positive squares in 4 ways, for example, as 1547536 + 19686969 = 1244^2 + 4437^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21234505 - 2¹¹ = 21232457 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21234509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2362 + ... + 6931.

It is an arithmetic number, because the mean of its divisors is an integer number (3192489).

Almost surely, 2^21234505 is an apocalyptic number.

It is an amenable number.

21234505 is a deficient number, since it is larger than the sum of its proper divisors (4305407).

21234505 is an equidigital number, since it uses as much as digits as its factorization.

21234505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9755.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21234505 is about 4608.0912534367. The cubic root of 21234505 is about 276.9155733267.

Adding to 21234505 its reverse (50543212), we get a palindrome (71777717).

The spelling of 21234505 in words is "twenty-one million, two hundred thirty-four thousand, five hundred five".