21542668 has 24 divisors (see below), whose sum is σ = 43635200. Its totient is φ = 9114768.

The previous prime is 21542663. The next prime is 21542681. The reversal of 21542668 is 86624512.

It is not an unprimeable number, because it can be changed into a prime (21542663) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 2658 + ... + 7081.

Almost surely, 2^21542668 is an apocalyptic number.

21542668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21542668 is an abundant number, since it is smaller than the sum of its proper divisors (22092532).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21542668 is a wasteful number, since it uses less digits than its factorization.

21542668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9829 (or 9827 counting only the distinct ones).

The product of its digits is 23040, while the sum is 34.

The square root of 21542668 is about 4641.4079760349. The cubic root of 21542668 is about 278.2487120891.

The spelling of 21542668 in words is "twenty-one million, five hundred forty-two thousand, six hundred sixty-eight".