21677218 has 4 divisors (see below), whose sum is σ = 32515830. Its totient is φ = 10838608.

The previous prime is 21677213. The next prime is 21677221. The reversal of 21677218 is 81277612.

It is a happy number.

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., 17665209 + 4012009 = 4203^2 + 2003^2 .

It is not an unprimeable number, because it can be changed into a prime (21677213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5419303 + ... + 5419306.

Almost surely, 2^21677218 is an apocalyptic number.

21677218 is a deficient number, since it is larger than the sum of its proper divisors (10838612).

21677218 is a wasteful number, since it uses less digits than its factorization.

21677218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10838611.

The product of its digits is 9408, while the sum is 34.

The square root of 21677218 is about 4655.8799383146. The cubic root of 21677218 is about 278.8268003442.

The spelling of 21677218 in words is "twenty-one million, six hundred seventy-seven thousand, two hundred eighteen".