21359979 has 12 divisors (see below), whose sum is σ = 31917600. Its totient is φ = 13748784.

The previous prime is 21359977. The next prime is 21359983. The reversal of 21359979 is 97995312.

It is a happy number.

It is not a de Polignac number, because 21359979 - 2¹ = 21359977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21359977) 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, 40659 + ... + 41180.

It is an arithmetic number, because the mean of its divisors is an integer number (2659800).

Almost surely, 2^21359979 is an apocalyptic number.

21359979 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21359979 is a deficient number, since it is larger than the sum of its proper divisors (10557621).

21359979 is a wasteful number, since it uses less digits than its factorization.

21359979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81874 (or 81871 counting only the distinct ones).

The product of its digits is 153090, while the sum is 45.

The square root of 21359979 is about 4621.6857314188. The cubic root of 21359979 is about 277.4599309080.

It can be divided in two parts, 21 and 359979, that added together give a square (360000 = 600²).

The spelling of 21359979 in words is "twenty-one million, three hundred fifty-nine thousand, nine hundred seventy-nine".