21568851 has 6 divisors (see below), whose sum is σ = 31155020. Its totient is φ = 14379228.

The previous prime is 21568849. The next prime is 21568861. The reversal of 21568851 is 15886512.

It is not a de Polignac number, because 21568851 - 2¹ = 21568849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21568831) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1198261 + ... + 1198278.

Almost surely, 2^21568851 is an apocalyptic number.

21568851 is a deficient number, since it is larger than the sum of its proper divisors (9586169).

21568851 is a wasteful number, since it uses less digits than its factorization.

21568851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2396545 (or 2396542 counting only the distinct ones).

The product of its digits is 19200, while the sum is 36.

The square root of 21568851 is about 4644.2277075957. The cubic root of 21568851 is about 278.3613944561.

The spelling of 21568851 in words is "twenty-one million, five hundred sixty-eight thousand, eight hundred fifty-one".