21107447 has 4 divisors (see below), whose sum is σ = 21835320. Its totient is φ = 20379576.

The previous prime is 21107417. The next prime is 21107467. The reversal of 21107447 is 74470112.

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

It is not a de Polignac number, because 21107447 - 2²⁴ = 4330231 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21107407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363893 + ... + 363950.

It is an arithmetic number, because the mean of its divisors is an integer number (5458830).

Almost surely, 2^21107447 is an apocalyptic number.

21107447 is a deficient number, since it is larger than the sum of its proper divisors (727873).

21107447 is an equidigital number, since it uses as much as digits as its factorization.

21107447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727872.

The product of its (nonzero) digits is 1568, while the sum is 26.

The square root of 21107447 is about 4594.2841662222. The cubic root of 21107447 is about 276.3621541153.

Adding to 21107447 its reverse (74470112), we get a palindrome (95577559).

The spelling of 21107447 in words is "twenty-one million, one hundred seven thousand, four hundred forty-seven".