21380909 has 8 divisors (see below), whose sum is σ = 24552480. Its totient is φ = 18414000.

The previous prime is 21380893. The next prime is 21380921. The reversal of 21380909 is 90908312.

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

It is not a de Polignac number, because 21380909 - 2⁴ = 21380893 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380929) 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, 50942 + ... + 51359.

It is an arithmetic number, because the mean of its divisors is an integer number (3069060).

Almost surely, 2^21380909 is an apocalyptic number.

It is an amenable number.

21380909 is a deficient number, since it is larger than the sum of its proper divisors (3171571).

21380909 is a wasteful number, since it uses less digits than its factorization.

21380909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102331.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21380909 is about 4623.9495023194. The cubic root of 21380909 is about 277.5505262001.

The spelling of 21380909 in words is "twenty-one million, three hundred eighty thousand, nine hundred nine".