21309379 has 12 divisors (see below), whose sum is σ = 26372496. Its totient is φ = 16859232.

The previous prime is 21309341. The next prime is 21309383. The reversal of 21309379 is 97390312.

It is not a de Polignac number, because 21309379 - 2⁹ = 21308867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21309319) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7824 + ... + 10189.

It is an arithmetic number, because the mean of its divisors is an integer number (2197708).

Almost surely, 2^21309379 is an apocalyptic number.

21309379 is a deficient number, since it is larger than the sum of its proper divisors (5063117).

21309379 is a wasteful number, since it uses less digits than its factorization.

21309379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18046 (or 18033 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 21309379 is about 4616.2082925275. The cubic root of 21309379 is about 277.2406645684.

The spelling of 21309379 in words is "twenty-one million, three hundred nine thousand, three hundred seventy-nine".