21442819 has 2 divisors, whose sum is σ = 21442820. Its totient is φ = 21442818.

The previous prime is 21442777. The next prime is 21442871. The reversal of 21442819 is 91824412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21442819 - 2⁹ = 21442307 is a prime.

It is a super-2 number, since 2×21442819² = 919588973333522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21442019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721409 + 10721410.

It is an arithmetic number, because the mean of its divisors is an integer number (10721410).

Almost surely, 2^21442819 is an apocalyptic number.

21442819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21442819 is an equidigital number, since it uses as much as digits as its factorization.

21442819 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 31.

The square root of 21442819 is about 4630.6391567472. The cubic root of 21442819 is about 277.8181573951.

The spelling of 21442819 in words is "twenty-one million, four hundred forty-two thousand, eight hundred nineteen".