21668115 has 64 divisors (see below), whose sum is σ = 42854400. Its totient is φ = 9123840.

The previous prime is 21668111. The next prime is 21668123. The reversal of 21668115 is 51186612.

It is not a de Polignac number, because 21668115 - 2² = 21668111 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21668111) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 108786 + ... + 108984.

It is an arithmetic number, because the mean of its divisors is an integer number (669600).

Almost surely, 2^21668115 is an apocalyptic number.

21668115 is a deficient number, since it is larger than the sum of its proper divisors (21186285).

21668115 is a wasteful number, since it uses less digits than its factorization.

21668115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 292.

The product of its digits is 2880, while the sum is 30.

The square root of 21668115 is about 4654.9022546129. The cubic root of 21668115 is about 278.7877652654.

The spelling of 21668115 in words is "twenty-one million, six hundred sixty-eight thousand, one hundred fifteen".