21805699 has 2 divisors, whose sum is σ = 21805700. Its totient is φ = 21805698.

The previous prime is 21805681. The next prime is 21805739. The reversal of 21805699 is 99650812.

It is an a-pointer prime, because the next prime (21805739) can be obtained adding 21805699 to its sum of digits (40).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21805699 - 2⁷ = 21805571 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21805639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902849 + 10902850.

It is an arithmetic number, because the mean of its divisors is an integer number (10902850).

Almost surely, 2^21805699 is an apocalyptic number.

21805699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21805699 is an equidigital number, since it uses as much as digits as its factorization.

21805699 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 21805699 is about 4669.6572679373. The cubic root of 21805699 is about 279.3765849463.

The spelling of 21805699 in words is "twenty-one million, eight hundred five thousand, six hundred ninety-nine".