21315669 has 4 divisors (see below), whose sum is σ = 28420896. Its totient is φ = 14210444.

The previous prime is 21315661. The next prime is 21315689. The reversal of 21315669 is 96651312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21315669 - 2³ = 21315661 is a prime.

It is a super-2 number, since 2×21315669² = 908715489835122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3552609 + ... + 3552614.

It is an arithmetic number, because the mean of its divisors is an integer number (7105224).

Almost surely, 2^21315669 is an apocalyptic number.

It is an amenable number.

21315669 is a deficient number, since it is larger than the sum of its proper divisors (7105227).

21315669 is an equidigital number, since it uses as much as digits as its factorization.

21315669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7105226.

The product of its digits is 9720, while the sum is 33.

The square root of 21315669 is about 4616.8895373400. The cubic root of 21315669 is about 277.2679400735.

The spelling of 21315669 in words is "twenty-one million, three hundred fifteen thousand, six hundred sixty-nine".