21563914 has 4 divisors (see below), whose sum is σ = 32345874. Its totient is φ = 10781956.

The previous prime is 21563897. The next prime is 21563923. The reversal of 21563914 is 41936512.

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

It can be written as a sum of positive squares in only one way, i.e., 21464689 + 99225 = 4633^2 + 315^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5390977 + ... + 5390980.

Almost surely, 2^21563914 is an apocalyptic number.

21563914 is a deficient number, since it is larger than the sum of its proper divisors (10781960).

21563914 is a wasteful number, since it uses less digits than its factorization.

21563914 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10781959.

The product of its digits is 6480, while the sum is 31.

The square root of 21563914 is about 4643.6961571576. The cubic root of 21563914 is about 278.3401543342.

The spelling of 21563914 in words is "twenty-one million, five hundred sixty-three thousand, nine hundred fourteen".