21579247 has 2 divisors, whose sum is σ = 21579248. Its totient is φ = 21579246.

The previous prime is 21579241. The next prime is 21579263. The reversal of 21579247 is 74297512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21579247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21579241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10789623 + 10789624.

It is an arithmetic number, because the mean of its divisors is an integer number (10789624).

Almost surely, 2^21579247 is an apocalyptic number.

21579247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21579247 is an equidigital number, since it uses as much as digits as its factorization.

21579247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 37.

The square root of 21579247 is about 4645.3468115954. The cubic root of 21579247 is about 278.4061098692.

The spelling of 21579247 in words is "twenty-one million, five hundred seventy-nine thousand, two hundred forty-seven".