21380015 has 8 divisors (see below), whose sum is σ = 25710048. Its totient is φ = 17068000.

The previous prime is 21380011. The next prime is 21380027. The reversal of 21380015 is 51008312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21380015 - 2² = 21380011 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380011) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1736 + ... + 6765.

It is an arithmetic number, because the mean of its divisors is an integer number (3213756).

Almost surely, 2^21380015 is an apocalyptic number.

21380015 is a deficient number, since it is larger than the sum of its proper divisors (4330033).

21380015 is an equidigital number, since it uses as much as digits as its factorization.

21380015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9009.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21380015 is about 4623.8528307030. The cubic root of 21380015 is about 277.5466577392.

Adding to 21380015 its reverse (51008312), we get a palindrome (72388327).

The spelling of 21380015 in words is "twenty-one million, three hundred eighty thousand, fifteen".