21378452 has 48 divisors (see below), whose sum is σ = 42230160. Its totient is φ = 9418752.

The previous prime is 21378443. The next prime is 21378457. The reversal of 21378452 is 25487312.

It can be written as a sum of positive squares in 8 ways, for example, as 8099716 + 13278736 = 2846^2 + 3644^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21378457) 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 in 15 ways as a sum of consecutive naturals, for example, 72818 + ... + 73110.

It is an arithmetic number, because the mean of its divisors is an integer number (879795).

Almost surely, 2^21378452 is an apocalyptic number.

It is an amenable number.

21378452 is a deficient number, since it is larger than the sum of its proper divisors (20851708).

21378452 is a wasteful number, since it uses less digits than its factorization.

21378452 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 380 (or 378 counting only the distinct ones).

The product of its digits is 13440, while the sum is 32.

The square root of 21378452 is about 4623.6838127190. The cubic root of 21378452 is about 277.5398941643.

The spelling of 21378452 in words is "twenty-one million, three hundred seventy-eight thousand, four hundred fifty-two".