21890170 has 8 divisors (see below), whose sum is σ = 39402324. Its totient is φ = 8756064.

The previous prime is 21890159. The next prime is 21890201. The reversal of 21890170 is 7109812.

It can be written as a sum of positive squares in 2 ways, for example, as 21261321 + 628849 = 4611^2 + 793^2 .

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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1094499 + ... + 1094518.

Almost surely, 2^21890170 is an apocalyptic number.

21890170 is a deficient number, since it is larger than the sum of its proper divisors (17512154).

21890170 is a wasteful number, since it uses less digits than its factorization.

21890170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2189024.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 21890170 is about 4678.6931936172. The cubic root of 21890170 is about 279.7368701483.

Adding to 21890170 its reverse (7109812), we get a palindrome (28999982).

The spelling of 21890170 in words is "twenty-one million, eight hundred ninety thousand, one hundred seventy".