21810706 has 4 divisors (see below), whose sum is σ = 32716062. Its totient is φ = 10905352.

The previous prime is 21810683. The next prime is 21810713. The reversal of 21810706 is 60701812.

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., 12538681 + 9272025 = 3541^2 + 3045^2 .

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 as a sum of consecutive naturals, namely, 5452675 + ... + 5452678.

Almost surely, 2^21810706 is an apocalyptic number.

21810706 is a deficient number, since it is larger than the sum of its proper divisors (10905356).

21810706 is a wasteful number, since it uses less digits than its factorization.

21810706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10905355.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21810706 is about 4670.1933578814. The cubic root of 21810706 is about 279.3979666886.

The spelling of 21810706 in words is "twenty-one million, eight hundred ten thousand, seven hundred six".