21668831 has 8 divisors (see below), whose sum is σ = 22164480. Its totient is φ = 21178872.

The previous prime is 21668827. The next prime is 21668839. The reversal of 21668831 is 13886612.

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 21668831 - 2² = 21668827 is a prime.

It is a super-2 number, since 2×21668831² = 939076473813122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21668791 and 21668800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21668839) 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, 6806 + ... + 9468.

It is an arithmetic number, because the mean of its divisors is an integer number (2770560).

Almost surely, 2^21668831 is an apocalyptic number.

21668831 is a deficient number, since it is larger than the sum of its proper divisors (495649).

21668831 is a wasteful number, since it uses less digits than its factorization.

21668831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2845.

The product of its digits is 13824, while the sum is 35.

The square root of 21668831 is about 4654.9791621446. The cubic root of 21668831 is about 278.7908359808.

The spelling of 21668831 in words is "twenty-one million, six hundred sixty-eight thousand, eight hundred thirty-one".