21471247 has 8 divisors (see below), whose sum is σ = 24574976. Its totient is φ = 18376632.

The previous prime is 21471239. The next prime is 21471257. The reversal of 21471247 is 74217412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21471247 - 2³ = 21471239 is a prime.

It is a super-2 number, since 2×21471247² = 922028895470018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471257) 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 7 ways as a sum of consecutive naturals, for example, 3898 + ... + 7624.

It is an arithmetic number, because the mean of its divisors is an integer number (3071872).

Almost surely, 2^21471247 is an apocalyptic number.

21471247 is a deficient number, since it is larger than the sum of its proper divisors (3103729).

21471247 is an equidigital number, since it uses as much as digits as its factorization.

21471247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4557.

The product of its digits is 3136, while the sum is 28.

The square root of 21471247 is about 4633.7076947084. The cubic root of 21471247 is about 277.9408764422.

Adding to 21471247 its reverse (74217412), we get a palindrome (95688659).

The spelling of 21471247 in words is "twenty-one million, four hundred seventy-one thousand, two hundred forty-seven".