21357579 has 4 divisors (see below), whose sum is σ = 28476776. Its totient is φ = 14238384.

The previous prime is 21357563. The next prime is 21357617. The reversal of 21357579 is 97575312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21357579 - 2⁴ = 21357563 is a prime.

It is a super-2 number, since 2×21357579² = 912292361482482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21357509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3559594 + ... + 3559599.

It is an arithmetic number, because the mean of its divisors is an integer number (7119194).

Almost surely, 2^21357579 is an apocalyptic number.

21357579 is a deficient number, since it is larger than the sum of its proper divisors (7119197).

21357579 is an equidigital number, since it uses as much as digits as its factorization.

21357579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7119196.

The product of its digits is 66150, while the sum is 39.

The square root of 21357579 is about 4621.4260786039. The cubic root of 21357579 is about 277.4495387509.

The spelling of 21357579 in words is "twenty-one million, three hundred fifty-seven thousand, five hundred seventy-nine".