20669621 has 12 divisors (see below), whose sum is σ = 24263532. Its totient is φ = 17555328.

The previous prime is 20669611. The next prime is 20669641. The reversal of 20669621 is 12696602.

It can be written as a sum of positive squares in 2 ways, for example, as 4468996 + 16200625 = 2114^2 + 4025^2 .

It is not a de Polignac number, because 20669621 - 2¹⁸ = 20407477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20669611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3671 + ... + 7403.

It is an arithmetic number, because the mean of its divisors is an integer number (2021961).

Almost surely, 2^20669621 is an apocalyptic number.

It is an amenable number.

20669621 is a deficient number, since it is larger than the sum of its proper divisors (3593911).

20669621 is a wasteful number, since it uses less digits than its factorization.

20669621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3860 (or 3853 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 20669621 is about 4546.3854873955. The cubic root of 20669621 is about 274.4379528928.

The spelling of 20669621 in words is "twenty million, six hundred sixty-nine thousand, six hundred twenty-one".