21669915 has 8 divisors (see below), whose sum is σ = 34671888. Its totient is φ = 11557280.

The previous prime is 21669871. The next prime is 21669943. The reversal of 21669915 is 51996612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21669915 - 2⁷ = 21669787 is a prime.

It is a super-2 number, since 2×21669915² = 939170432214450, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 722316 + ... + 722345.

It is an arithmetic number, because the mean of its divisors is an integer number (4333986).

Almost surely, 2^21669915 is an apocalyptic number.

21669915 is a deficient number, since it is larger than the sum of its proper divisors (13001973).

21669915 is a wasteful number, since it uses less digits than its factorization.

21669915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1444669.

The product of its digits is 29160, while the sum is 39.

The square root of 21669915 is about 4655.0955951516. The cubic root of 21669915 is about 278.7954848122.

The spelling of 21669915 in words is "twenty-one million, six hundred sixty-nine thousand, nine hundred fifteen".