21005319 has 16 divisors (see below), whose sum is σ = 29795040. Its totient is φ = 13117440.

The previous prime is 21005311. The next prime is 21005329. The reversal of 21005319 is 91350012.

It is not a de Polignac number, because 21005319 - 2³ = 21005311 is a prime.

It is a super-2 number, since 2×21005319² = 882446852583522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21005295 and 21005304.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11437 + ... + 13145.

It is an arithmetic number, because the mean of its divisors is an integer number (1862190).

Almost surely, 2^21005319 is an apocalyptic number.

21005319 is a deficient number, since it is larger than the sum of its proper divisors (8789721).

21005319 is a wasteful number, since it uses less digits than its factorization.

21005319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1970.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21005319 is about 4583.1560086910. The cubic root of 21005319 is about 275.9157088745.

The spelling of 21005319 in words is "twenty-one million, five thousand, three hundred nineteen".