21380471 has 4 divisors (see below), whose sum is σ = 24434832. Its totient is φ = 18326112.

The previous prime is 21380467. The next prime is 21380473. The reversal of 21380471 is 17408312.

21380471 = 999² + 1000² + ... + 1019².

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

It is not a de Polignac number, because 21380471 - 2² = 21380467 is a prime.

It is a super-3 number, since 3×21380471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 21380471.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380473) 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, 1527170 + ... + 1527183.

It is an arithmetic number, because the mean of its divisors is an integer number (6108708).

Almost surely, 2^21380471 is an apocalyptic number.

21380471 is a deficient number, since it is larger than the sum of its proper divisors (3054361).

21380471 is an equidigital number, since it uses as much as digits as its factorization.

21380471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3054360.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21380471 is about 4623.9021399679. The cubic root of 21380471 is about 277.5486309274.

Adding to 21380471 its reverse (17408312), we get a palindrome (38788783).

The spelling of 21380471 in words is "twenty-one million, three hundred eighty thousand, four hundred seventy-one".