21616705 has 8 divisors (see below), whose sum is σ = 28298304. Its totient is φ = 15721200.

The previous prime is 21616697. The next prime is 21616729. The reversal of 21616705 is 50761612.

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

It is not a de Polignac number, because 21616705 - 2³ = 21616697 is a prime.

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

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 196461 + ... + 196570.

It is an arithmetic number, because the mean of its divisors is an integer number (3537288).

Almost surely, 2^21616705 is an apocalyptic number.

It is an amenable number.

21616705 is a deficient number, since it is larger than the sum of its proper divisors (6681599).

21616705 is a wasteful number, since it uses less digits than its factorization.

21616705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393047.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21616705 is about 4649.3768399647. The cubic root of 21616705 is about 278.5671057217.

The spelling of 21616705 in words is "twenty-one million, six hundred sixteen thousand, seven hundred five".