20455621 has 4 divisors (see below), whose sum is σ = 20475052. Its totient is φ = 20436192.

The previous prime is 20455601. The next prime is 20455627. The reversal of 20455621 is 12655402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2604996 + 17850625 = 1614^2 + 4225^2 .

It is a cyclic number.

It is not a de Polignac number, because 20455621 - 2⁹ = 20455109 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 (20455627) 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, 8040 + ... + 10273.

It is an arithmetic number, because the mean of its divisors is an integer number (5118763).

Almost surely, 2^20455621 is an apocalyptic number.

It is an amenable number.

20455621 is a deficient number, since it is larger than the sum of its proper divisors (19431).

20455621 is a wasteful number, since it uses less digits than its factorization.

20455621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19430.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 20455621 is about 4522.7890731273. The cubic root of 20455621 is about 273.4875471561.

The spelling of 20455621 in words is "twenty million, four hundred fifty-five thousand, six hundred twenty-one".