21407305 has 8 divisors (see below), whose sum is σ = 25718472. Its totient is φ = 17106048.

The previous prime is 21407297. The next prime is 21407317. The reversal of 21407305 is 50370412.

It can be written as a sum of positive squares in 4 ways, for example, as 284089 + 21123216 = 533^2 + 4596^2 .

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 21407305 - 2³ = 21407297 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3669 + ... + 7501.

It is an arithmetic number, because the mean of its divisors is an integer number (3214809).

Almost surely, 2^21407305 is an apocalyptic number.

It is an amenable number.

21407305 is a deficient number, since it is larger than the sum of its proper divisors (4311167).

21407305 is a wasteful number, since it uses less digits than its factorization.

21407305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4955.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21407305 is about 4626.8028918466. The cubic root of 21407305 is about 277.6646967571.

Adding to 21407305 its reverse (50370412), we get a palindrome (71777717).

It can be divided in two parts, 21407 and 305, that added together give a palindrome (21712).

The spelling of 21407305 in words is "twenty-one million, four hundred seven thousand, three hundred five".