21278116 has 6 divisors (see below), whose sum is σ = 37236710. Its totient is φ = 10639056.

The previous prime is 21278111. The next prime is 21278137. The reversal of 21278116 is 61187212.

It can be written as a sum of positive squares in only one way, i.e., 19838116 + 1440000 = 4454^2 + 1200^2 .

It is not an unprimeable number, because it can be changed into a prime (21278111) 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 as a sum of consecutive naturals, namely, 2659761 + ... + 2659768.

Almost surely, 2^21278116 is an apocalyptic number.

It is an amenable number.

21278116 is a deficient number, since it is larger than the sum of its proper divisors (15958594).

21278116 is a wasteful number, since it uses less digits than its factorization.

21278116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5319533 (or 5319531 counting only the distinct ones).

The product of its digits is 1344, while the sum is 28.

The square root of 21278116 is about 4612.8208289505. The cubic root of 21278116 is about 277.1050182412.

The spelling of 21278116 in words is "twenty-one million, two hundred seventy-eight thousand, one hundred sixteen".