21356378 has 4 divisors (see below), whose sum is σ = 32034570. Its totient is φ = 10678188.

The previous prime is 21356353. The next prime is 21356381. The reversal of 21356378 is 87365312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11135569 + 10220809 = 3337^2 + 3197^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5339093 + ... + 5339096.

Almost surely, 2^21356378 is an apocalyptic number.

21356378 is a deficient number, since it is larger than the sum of its proper divisors (10678192).

21356378 is a wasteful number, since it uses less digits than its factorization.

21356378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10678191.

The product of its digits is 30240, while the sum is 35.

The square root of 21356378 is about 4621.2961385308. The cubic root of 21356378 is about 277.4443380500. Note that the first 3 decimals are identical.

The spelling of 21356378 in words is "twenty-one million, three hundred fifty-six thousand, three hundred seventy-eight".