21556699 has 2 divisors, whose sum is σ = 21556700. Its totient is φ = 21556698.

The previous prime is 21556673. The next prime is 21556709. The reversal of 21556699 is 99665512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21556699 - 2¹¹ = 21554651 is a prime.

It is not a weakly prime, because it can be changed into another prime (21556649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10778349 + 10778350.

It is an arithmetic number, because the mean of its divisors is an integer number (10778350).

Almost surely, 2^21556699 is an apocalyptic number.

21556699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21556699 is an equidigital number, since it uses as much as digits as its factorization.

21556699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 43.

The square root of 21556699 is about 4642.9192325519. The cubic root of 21556699 is about 278.3091078951.

The spelling of 21556699 in words is "twenty-one million, five hundred fifty-six thousand, six hundred ninety-nine".