21668827 has 2 divisors, whose sum is σ = 21668828. Its totient is φ = 21668826.

The previous prime is 21668807. The next prime is 21668839. The reversal of 21668827 is 72886612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21668827 - 2¹¹ = 21666779 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21668827.

It is not a weakly prime, because it can be changed into another prime (21668807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10834413 + 10834414.

It is an arithmetic number, because the mean of its divisors is an integer number (10834414).

Almost surely, 2^21668827 is an apocalyptic number.

21668827 is a deficient number, since it is larger than the sum of its proper divisors (1).

21668827 is an equidigital number, since it uses as much as digits as its factorization.

21668827 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 40.

The square root of 21668827 is about 4654.9787324971. The cubic root of 21668827 is about 278.7908188262.

The spelling of 21668827 in words is "twenty-one million, six hundred sixty-eight thousand, eight hundred twenty-seven".