21158668 has 6 divisors (see below), whose sum is σ = 37027676. Its totient is φ = 10579332.

The previous prime is 21158633. The next prime is 21158671. The reversal of 21158668 is 86685112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2644830 + ... + 2644837.

Almost surely, 2^21158668 is an apocalyptic number.

It is an amenable number.

21158668 is a deficient number, since it is larger than the sum of its proper divisors (15869008).

21158668 is a wasteful number, since it uses less digits than its factorization.

21158668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5289671 (or 5289669 counting only the distinct ones).

The product of its digits is 23040, while the sum is 37.

The square root of 21158668 is about 4599.8552151128. The cubic root of 21158668 is about 276.5855209517.

The spelling of 21158668 in words is "twenty-one million, one hundred fifty-eight thousand, six hundred sixty-eight".