21666202 has 4 divisors (see below), whose sum is σ = 32499306. Its totient is φ = 10833100.

The previous prime is 21666191. The next prime is 21666209. The reversal of 21666202 is 20266612.

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., 20784481 + 881721 = 4559^2 + 939^2 .

It is not an unprimeable number, because it can be changed into a prime (21666209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5416549 + ... + 5416552.

Almost surely, 2^21666202 is an apocalyptic number.

21666202 is a deficient number, since it is larger than the sum of its proper divisors (10833104).

21666202 is a wasteful number, since it uses less digits than its factorization.

21666202 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10833103.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21666202 is about 4654.6967677820. The cubic root of 21666202 is about 278.7795606340.

The spelling of 21666202 in words is "twenty-one million, six hundred sixty-six thousand, two hundred two".