21608851 has 8 divisors (see below), whose sum is σ = 24210864. Its totient is φ = 19113120.

The previous prime is 21608837. The next prime is 21608893. The reversal of 21608851 is 15880612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21608851 - 2²³ = 13220243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21608831) 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 7 ways as a sum of consecutive naturals, for example, 26140 + ... + 26953.

It is an arithmetic number, because the mean of its divisors is an integer number (3026358).

Almost surely, 2^21608851 is an apocalyptic number.

21608851 is a deficient number, since it is larger than the sum of its proper divisors (2602013).

21608851 is a wasteful number, since it uses less digits than its factorization.

21608851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53141.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 21608851 is about 4648.5321339107. The cubic root of 21608851 is about 278.5333643617.

It can be divided in two parts, 2160 and 8851, that added together give a palindrome (11011).

The spelling of 21608851 in words is "twenty-one million, six hundred eight thousand, eight hundred fifty-one".