21105378 has 36 divisors (see below), whose sum is σ = 53196390. Its totient is φ = 6029856.

The previous prime is 21105367. The next prime is 21105391. The reversal of 21105378 is 87350112.

It can be written as a sum of positive squares in only one way, i.e., 16426809 + 4678569 = 4053^2 + 2163^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11083 + ... + 12846.

Almost surely, 2^21105378 is an apocalyptic number.

21105378 is an abundant number, since it is smaller than the sum of its proper divisors (32091012).

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

21105378 is a wasteful number, since it uses less digits than its factorization.

21105378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23951 (or 23941 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21105378 is about 4594.0589896082. The cubic root of 21105378 is about 276.3531239378.

The spelling of 21105378 in words is "twenty-one million, one hundred five thousand, three hundred seventy-eight".