20655221 has 8 divisors (see below), whose sum is σ = 22624920. Its totient is φ = 18769408.

The previous prime is 20655203. The next prime is 20655227. The reversal of 20655221 is 12255602.

It can be written as a sum of positive squares in 4 ways, for example, as 7623121 + 13032100 = 2761^2 + 3610^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20655221 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 (20655227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20456 + ... + 21441.

It is an arithmetic number, because the mean of its divisors is an integer number (2828115).

Almost surely, 2^20655221 is an apocalyptic number.

It is an amenable number.

20655221 is a deficient number, since it is larger than the sum of its proper divisors (1969699).

20655221 is a wasteful number, since it uses less digits than its factorization.

20655221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41943.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 20655221 is about 4544.8015358209. The cubic root of 20655221 is about 274.3742067698.

The spelling of 20655221 in words is "twenty million, six hundred fifty-five thousand, two hundred twenty-one".