21355319 has 4 divisors (see below), whose sum is σ = 21612696. Its totient is φ = 21097944.

The previous prime is 21355291. The next prime is 21355351. The reversal of 21355319 is 91355312.

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

It is a cyclic number.

It is not a de Polignac number, because 21355319 - 2²⁴ = 4578103 is a prime.

It is a super-2 number, since 2×21355319² = 912099299183522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21355291 and 21355300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21325319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128564 + ... + 128729.

It is an arithmetic number, because the mean of its divisors is an integer number (5403174).

Almost surely, 2^21355319 is an apocalyptic number.

21355319 is a deficient number, since it is larger than the sum of its proper divisors (257377).

21355319 is an equidigital number, since it uses as much as digits as its factorization.

21355319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257376.

The product of its digits is 4050, while the sum is 29.

The square root of 21355319 is about 4621.1815588657. The cubic root of 21355319 is about 277.4397520911.

The spelling of 21355319 in words is "twenty-one million, three hundred fifty-five thousand, three hundred nineteen".