21345579 has 16 divisors (see below), whose sum is σ = 31917600. Its totient is φ = 14097888.

The previous prime is 21345539. The next prime is 21345589. The reversal of 21345579 is 97554312.

It is not a de Polignac number, because 21345579 - 2⁷ = 21345451 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21345509) 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, 684 + ... + 6569.

It is an arithmetic number, because the mean of its divisors is an integer number (1994850).

Almost surely, 2^21345579 is an apocalyptic number.

21345579 is a deficient number, since it is larger than the sum of its proper divisors (10572021).

21345579 is a wasteful number, since it uses less digits than its factorization.

21345579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7371 (or 7365 counting only the distinct ones).

The product of its digits is 37800, while the sum is 36.

The square root of 21345579 is about 4620.1275956406. The cubic root of 21345579 is about 277.3975662838.

The spelling of 21345579 in words is "twenty-one million, three hundred forty-five thousand, five hundred seventy-nine".