21530147 has 2 divisors, whose sum is σ = 21530148. Its totient is φ = 21530146.

The previous prime is 21530129. The next prime is 21530153. The reversal of 21530147 is 74103512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21530147 - 2⁸ = 21529891 is a prime.

It is a Chen prime.

It is equal to p_1361354 and since 21530147 and 1361354 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21530447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765073 + 10765074.

It is an arithmetic number, because the mean of its divisors is an integer number (10765074).

Almost surely, 2^21530147 is an apocalyptic number.

21530147 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530147 is an equidigital number, since it uses as much as digits as its factorization.

21530147 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21530147 is about 4640.0589435911. The cubic root of 21530147 is about 278.1947938632.

Adding to 21530147 its reverse (74103512), we get a palindrome (95633659).

The spelling of 21530147 in words is "twenty-one million, five hundred thirty thousand, one hundred forty-seven".