669621 has 4 divisors (see below), whose sum is σ = 892832. Its totient is φ = 446412.

The previous prime is 669611. The next prime is 669637. The reversal of 669621 is 126966.

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 de Polignac number, because none of the positive numbers 2^k-669621 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 669621.

It is not an unprimeable number, because it can be changed into a prime (669611) 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, 111601 + ... + 111606.

It is an arithmetic number, because the mean of its divisors is an integer number (223208).

2⁶⁶⁹⁶²¹ is an apocalyptic number.

It is an amenable number.

669621 is a deficient number, since it is larger than the sum of its proper divisors (223211).

669621 is a wasteful number, since it uses less digits than its factorization.

669621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223210.

The product of its digits is 3888, while the sum is 30.

The square root of 669621 is about 818.3037333411. The cubic root of 669621 is about 87.4868987187.

The spelling of 669621 in words is "six hundred sixty-nine thousand, six hundred twenty-one".