21490819 has 4 divisors (see below), whose sum is σ = 24560944. Its totient is φ = 18420696.

The previous prime is 21490789. The next prime is 21490867. The reversal of 21490819 is 91809412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21490819 - 2²¹ = 19393667 is a prime.

It is a super-2 number, since 2×21490819² = 923710602581522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21490879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1535052 + ... + 1535065.

It is an arithmetic number, because the mean of its divisors is an integer number (6140236).

Almost surely, 2^21490819 is an apocalyptic number.

21490819 is a deficient number, since it is larger than the sum of its proper divisors (3070125).

21490819 is an equidigital number, since it uses as much as digits as its factorization.

21490819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3070124.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21490819 is about 4635.8191293449. The cubic root of 21490819 is about 278.0253026329.

The spelling of 21490819 in words is "twenty-one million, four hundred ninety thousand, eight hundred nineteen".