21383979 has 4 divisors (see below), whose sum is σ = 28511976. Its totient is φ = 14255984.

The previous prime is 21383969. The next prime is 21384061. The reversal of 21383979 is 97938312.

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 21383979 - 2⁸ = 21383723 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21383979.

It is not an unprimeable number, because it can be changed into a prime (21383969) 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, 3563994 + ... + 3563999.

It is an arithmetic number, because the mean of its divisors is an integer number (7127994).

Almost surely, 2^21383979 is an apocalyptic number.

21383979 is a deficient number, since it is larger than the sum of its proper divisors (7127997).

21383979 is an equidigital number, since it uses as much as digits as its factorization.

21383979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7127996.

The product of its digits is 81648, while the sum is 42.

The square root of 21383979 is about 4624.2814576970. The cubic root of 21383979 is about 277.5638096911.

The spelling of 21383979 in words is "twenty-one million, three hundred eighty-three thousand, nine hundred seventy-nine".