21656479 has 8 divisors (see below), whose sum is σ = 23541840. Its totient is φ = 19802496.

The previous prime is 21656461. The next prime is 21656513. The reversal of 21656479 is 97465612.

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 21656479 - 2¹⁷ = 21525407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656429) 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, 6394 + ... + 9175.

It is an arithmetic number, because the mean of its divisors is an integer number (2942730).

Almost surely, 2^21656479 is an apocalyptic number.

21656479 is a deficient number, since it is larger than the sum of its proper divisors (1885361).

21656479 is a wasteful number, since it uses less digits than its factorization.

21656479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15689.

The product of its digits is 90720, while the sum is 40.

The square root of 21656479 is about 4653.6522216427. The cubic root of 21656479 is about 278.7378523667.

The spelling of 21656479 in words is "twenty-one million, six hundred fifty-six thousand, four hundred seventy-nine".