21691283 has 2 divisors, whose sum is σ = 21691284. Its totient is φ = 21691282.

The previous prime is 21691279. The next prime is 21691309. The reversal of 21691283 is 38219612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21691283 - 2² = 21691279 is a prime.

It is not a weakly prime, because it can be changed into another prime (21691223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10845641 + 10845642.

It is an arithmetic number, because the mean of its divisors is an integer number (10845642).

Almost surely, 2^21691283 is an apocalyptic number.

21691283 is a deficient number, since it is larger than the sum of its proper divisors (1).

21691283 is an equidigital number, since it uses as much as digits as its factorization.

21691283 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 21691283 is about 4657.3901489998. The cubic root of 21691283 is about 278.8870917689.

The spelling of 21691283 in words is "twenty-one million, six hundred ninety-one thousand, two hundred eighty-three".