21707999 has 2 divisors, whose sum is σ = 21708000. Its totient is φ = 21707998.

The previous prime is 21707981. The next prime is 21708007. The reversal of 21707999 is 99970712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21707999 - 2⁸ = 21707743 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21707909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10853999 + 10854000.

It is an arithmetic number, because the mean of its divisors is an integer number (10854000).

Almost surely, 2^21707999 is an apocalyptic number.

21707999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21707999 is an equidigital number, since it uses as much as digits as its factorization.

21707999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 71442, while the sum is 44.

The square root of 21707999 is about 4659.1843706812. The cubic root of 21707999 is about 278.9587131602.

The spelling of 21707999 in words is "twenty-one million, seven hundred seven thousand, nine hundred ninety-nine".