21878116 has 24 divisors (see below), whose sum is σ = 43659000. Its totient is φ = 9503232.

The previous prime is 21878111. The next prime is 21878123. The reversal of 21878116 is 61187812.

It can be written as a sum of positive squares in 4 ways, for example, as 8526400 + 13351716 = 2920^2 + 3654^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21878111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11491 + ... + 13258.

It is an arithmetic number, because the mean of its divisors is an integer number (1819125).

Almost surely, 2^21878116 is an apocalyptic number.

21878116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21878116 is a deficient number, since it is larger than the sum of its proper divisors (21780884).

21878116 is a wasteful number, since it uses less digits than its factorization.

21878116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24783 (or 24781 counting only the distinct ones).

The product of its digits is 5376, while the sum is 34.

The square root of 21878116 is about 4677.4048360175. The cubic root of 21878116 is about 279.6855142603.

The spelling of 21878116 in words is "twenty-one million, eight hundred seventy-eight thousand, one hundred sixteen".