21663514 has 4 divisors (see below), whose sum is σ = 32495274. Its totient is φ = 10831756.

The previous prime is 21663511. The next prime is 21663527. The reversal of 21663514 is 41536612.

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., 16524225 + 5139289 = 4065^2 + 2267^2 .

It is not an unprimeable number, because it can be changed into a prime (21663511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5415877 + ... + 5415880.

Almost surely, 2^21663514 is an apocalyptic number.

21663514 is a deficient number, since it is larger than the sum of its proper divisors (10831760).

21663514 is a wasteful number, since it uses less digits than its factorization.

21663514 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10831759.

The product of its digits is 4320, while the sum is 28.

The square root of 21663514 is about 4654.4080182124. The cubic root of 21663514 is about 278.7680313029.

The spelling of 21663514 in words is "twenty-one million, six hundred sixty-three thousand, five hundred fourteen".