21242178 has 12 divisors (see below), whose sum is σ = 46024758. Its totient is φ = 7080720.

The previous prime is 21242153. The next prime is 21242191. The reversal of 21242178 is 87124212.

It can be written as a sum of positive squares in only one way, i.e., 18429849 + 2812329 = 4293^2 + 1677^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 590043 + ... + 590078.

Almost surely, 2^21242178 is an apocalyptic number.

21242178 is an abundant number, since it is smaller than the sum of its proper divisors (24782580).

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

21242178 is a wasteful number, since it uses less digits than its factorization.

21242178 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1180129 (or 1180126 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21242178 is about 4608.9237355374. The cubic root of 21242178 is about 276.9489234066.

The spelling of 21242178 in words is "twenty-one million, two hundred forty-two thousand, one hundred seventy-eight".