21389379 has 16 divisors (see below), whose sum is σ = 32465664. Its totient is φ = 12399200.

The previous prime is 21389377. The next prime is 21389393. The reversal of 21389379 is 97398312.

It is not a de Polignac number, because 21389379 - 2¹ = 21389377 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21389379.

It is not an unprimeable number, because it can be changed into a prime (21389377) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13332 + ... + 14849.

It is an arithmetic number, because the mean of its divisors is an integer number (2029104).

Almost surely, 2^21389379 is an apocalyptic number.

21389379 is a deficient number, since it is larger than the sum of its proper divisors (11076285).

21389379 is a wasteful number, since it uses less digits than its factorization.

21389379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28218.

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

The square root of 21389379 is about 4624.8652953356. The cubic root of 21389379 is about 277.5871717047.

The spelling of 21389379 in words is "twenty-one million, three hundred eighty-nine thousand, three hundred seventy-nine".