21438370 has 8 divisors (see below), whose sum is σ = 38589084. Its totient is φ = 8575344.

The previous prime is 21438359. The next prime is 21438401. The reversal of 21438370 is 7383412.

21438370 = 568² + 569² + ... + 627².

It can be written as a sum of positive squares in 2 ways, for example, as 21409129 + 29241 = 4627^2 + 171^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1071909 + ... + 1071928.

Almost surely, 2^21438370 is an apocalyptic number.

21438370 is a deficient number, since it is larger than the sum of its proper divisors (17150714).

21438370 is a wasteful number, since it uses less digits than its factorization.

21438370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2143844.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21438370 is about 4630.1587445789. The cubic root of 21438370 is about 277.7989419726.

The spelling of 21438370 in words is "twenty-one million, four hundred thirty-eight thousand, three hundred seventy".