21258378 has 48 divisors (see below), whose sum is σ = 49327200. Its totient is φ = 6596640.

The previous prime is 21258373. The next prime is 21258401. The reversal of 21258378 is 87385212.

21258378 is a `hidden beast` number, since 2 + 1 + 2 + 583 + 78 = 666.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21258373) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20353 + ... + 21371.

It is an arithmetic number, because the mean of its divisors is an integer number (1027650).

Almost surely, 2^21258378 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21258378, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24663600).

21258378 is an abundant number, since it is smaller than the sum of its proper divisors (28068822).

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

21258378 is a wasteful number, since it uses less digits than its factorization.

21258378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1107 (or 1104 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 21258378 is about 4610.6808607840. The cubic root of 21258378 is about 277.0193090408.

The spelling of 21258378 in words is "twenty-one million, two hundred fifty-eight thousand, three hundred seventy-eight".