21918347 has 16 divisors (see below), whose sum is σ = 24710400. Its totient is φ = 19269600.

The previous prime is 21918329. The next prime is 21918353. The reversal of 21918347 is 74381912.

It is a cyclic number.

It is not a de Polignac number, because 21918347 - 2¹² = 21914251 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21918307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70322 + ... + 70632.

It is an arithmetic number, because the mean of its divisors is an integer number (1544400).

Almost surely, 2^21918347 is an apocalyptic number.

21918347 is a deficient number, since it is larger than the sum of its proper divisors (2792053).

21918347 is a wasteful number, since it uses less digits than its factorization.

21918347 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514.

The product of its digits is 12096, while the sum is 35.

The square root of 21918347 is about 4681.7034293086. The cubic root of 21918347 is about 279.8568443383.

The spelling of 21918347 in words is "twenty-one million, nine hundred eighteen thousand, three hundred forty-seven".