21010819 has 12 divisors (see below), whose sum is σ = 22330080. Its totient is φ = 19745600.

The previous prime is 21010811. The next prime is 21010831. The reversal of 21010819 is 91801012.

It is not a de Polignac number, because 21010819 - 2³ = 21010811 is a prime.

It is a super-2 number, since 2×21010819² = 882909030101522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21010819.

It is not an unprimeable number, because it can be changed into a prime (21010811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 48534 + ... + 48964.

It is an arithmetic number, because the mean of its divisors is an integer number (1860840).

Almost surely, 2^21010819 is an apocalyptic number.

21010819 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21010819 is a deficient number, since it is larger than the sum of its proper divisors (1319261).

21010819 is an equidigital number, since it uses as much as digits as its factorization.

21010819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542 (or 501 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 21010819 is about 4583.7559926331. The cubic root of 21010819 is about 275.9397885527.

The spelling of 21010819 in words is "twenty-one million, ten thousand, eight hundred nineteen".