21669418 has 8 divisors (see below), whose sum is σ = 32802660. Its totient is φ = 10735200.

The previous prime is 21669371. The next prime is 21669493. The reversal of 21669418 is 81496612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21040569 + 628849 = 4587^2 + 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, 49483 + ... + 49918.

Almost surely, 2^21669418 is an apocalyptic number.

21669418 is a deficient number, since it is larger than the sum of its proper divisors (11133242).

21669418 is a wasteful number, since it uses less digits than its factorization.

21669418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99512.

The product of its digits is 20736, while the sum is 37.

The square root of 21669418 is about 4655.0422124831. The cubic root of 21669418 is about 278.7933534023.

The spelling of 21669418 in words is "twenty-one million, six hundred sixty-nine thousand, four hundred eighteen".