21170818 has 4 divisors (see below), whose sum is σ = 31756230. Its totient is φ = 10585408.

The previous prime is 21170789. The next prime is 21170857. The reversal of 21170818 is 81807112.

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., 16184529 + 4986289 = 4023^2 + 2233^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5292703 + ... + 5292706.

Almost surely, 2^21170818 is an apocalyptic number.

21170818 is a deficient number, since it is larger than the sum of its proper divisors (10585412).

21170818 is a wasteful number, since it uses less digits than its factorization.

21170818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10585411.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21170818 is about 4601.1757193135. The cubic root of 21170818 is about 276.6384523090.

The spelling of 21170818 in words is "twenty-one million, one hundred seventy thousand, eight hundred eighteen".