21447718 has 4 divisors (see below), whose sum is σ = 32171580. Its totient is φ = 10723858.

The previous prime is 21447709. The next prime is 21447719. The reversal of 21447718 is 81774412.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21447719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5361928 + ... + 5361931.

It is an arithmetic number, because the mean of its divisors is an integer number (8042895).

Almost surely, 2^21447718 is an apocalyptic number.

21447718 is a deficient number, since it is larger than the sum of its proper divisors (10723862).

21447718 is a wasteful number, since it uses less digits than its factorization.

21447718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10723861.

The product of its digits is 12544, while the sum is 34.

The square root of 21447718 is about 4631.1681031895. The cubic root of 21447718 is about 277.8393133123.

The spelling of 21447718 in words is "twenty-one million, four hundred forty-seven thousand, seven hundred eighteen".