21643562 has 4 divisors (see below), whose sum is σ = 32465346. Its totient is φ = 10821780.

The previous prime is 21643519. The next prime is 21643607. The reversal of 21643562 is 26534612.

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., 13169641 + 8473921 = 3629^2 + 2911^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5410889 + ... + 5410892.

Almost surely, 2^21643562 is an apocalyptic number.

21643562 is a deficient number, since it is larger than the sum of its proper divisors (10821784).

21643562 is a wasteful number, since it uses less digits than its factorization.

21643562 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10821783.

The product of its digits is 8640, while the sum is 29.

The square root of 21643562 is about 4652.2641799451. The cubic root of 21643562 is about 278.6824236440.

The spelling of 21643562 in words is "twenty-one million, six hundred forty-three thousand, five hundred sixty-two".