21999347 has 2 divisors, whose sum is σ = 21999348. Its totient is φ = 21999346.

The previous prime is 21999331. The next prime is 21999379. The reversal of 21999347 is 74399912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21999347 - 2⁴ = 21999331 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21999298 and 21999307.

It is not a weakly prime, because it can be changed into another prime (21999317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999673 + 10999674.

It is an arithmetic number, because the mean of its divisors is an integer number (10999674).

Almost surely, 2^21999347 is an apocalyptic number.

21999347 is a deficient number, since it is larger than the sum of its proper divisors (1).

21999347 is an equidigital number, since it uses as much as digits as its factorization.

21999347 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 44.

The square root of 21999347 is about 4690.3461492730. The cubic root of 21999347 is about 280.2011607174.

The spelling of 21999347 in words is "twenty-one million, nine hundred ninety-nine thousand, three hundred forty-seven".