21270709 has 8 divisors (see below), whose sum is σ = 22436000. Its totient is φ = 20110032.

The previous prime is 21270707. The next prime is 21270713. The reversal of 21270709 is 90707212.

It is a happy number.

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 21270709 - 2¹ = 21270707 is a prime.

It is a super-2 number, since 2×21270709² = 904886122725362, which contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21270707) 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, 12682 + ... + 14260.

It is an arithmetic number, because the mean of its divisors is an integer number (2804500).

Almost surely, 2^21270709 is an apocalyptic number.

It is an amenable number.

21270709 is a deficient number, since it is larger than the sum of its proper divisors (1165291).

21270709 is a wasteful number, since it uses less digits than its factorization.

21270709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2307.

The product of its (nonzero) digits is 1764, while the sum is 28.

The square root of 21270709 is about 4612.0178880833. The cubic root of 21270709 is about 277.0728607093.

The spelling of 21270709 in words is "twenty-one million, two hundred seventy thousand, seven hundred nine".