21396579 has 16 divisors (see below), whose sum is σ = 29122560. Its totient is φ = 13970880.

The previous prime is 21396569. The next prime is 21396587. The reversal of 21396579 is 97569312.

It is not a de Polignac number, because 21396579 - 2¹⁶ = 21331043 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21396579.

It is not an unprimeable number, because it can be changed into a prime (21396569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33594 + ... + 34224.

It is an arithmetic number, because the mean of its divisors is an integer number (1820160).

Almost surely, 2^21396579 is an apocalyptic number.

21396579 is a deficient number, since it is larger than the sum of its proper divisors (7725981).

21396579 is a wasteful number, since it uses less digits than its factorization.

21396579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850.

The product of its digits is 102060, while the sum is 42.

The square root of 21396579 is about 4625.6436308907. The cubic root of 21396579 is about 277.6183149405.

The spelling of 21396579 in words is "twenty-one million, three hundred ninety-six thousand, five hundred seventy-nine".