21055669 has 4 divisors (see below), whose sum is σ = 21065344. Its totient is φ = 21045996.

The previous prime is 21055663. The next prime is 21055679. The reversal of 21055669 is 96655012.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21055669 - 2¹⁵ = 21022901 is a prime.

It is a super-2 number, since 2×21055669² = 886682394075122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055663) 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, 124 + ... + 6490.

It is an arithmetic number, because the mean of its divisors is an integer number (5266336).

Almost surely, 2^21055669 is an apocalyptic number.

It is an amenable number.

21055669 is a deficient number, since it is larger than the sum of its proper divisors (9675).

21055669 is an equidigital number, since it uses as much as digits as its factorization.

21055669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9674.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 21055669 is about 4588.6456607587. The cubic root of 21055669 is about 276.1359907096.

The spelling of 21055669 in words is "twenty-one million, fifty-five thousand, six hundred sixty-nine".