20660421 has 4 divisors (see below), whose sum is σ = 27547232. Its totient is φ = 13773612.

The previous prime is 20660399. The next prime is 20660473. The reversal of 20660421 is 12406602.

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.

It is not a de Polignac number, because 20660421 - 2¹⁴ = 20644037 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 (20660621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3443401 + ... + 3443406.

It is an arithmetic number, because the mean of its divisors is an integer number (6886808).

Almost surely, 2^20660421 is an apocalyptic number.

It is an amenable number.

20660421 is a deficient number, since it is larger than the sum of its proper divisors (6886811).

20660421 is an equidigital number, since it uses as much as digits as its factorization.

20660421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6886810.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 20660421 is about 4545.3735820062. The cubic root of 20660421 is about 274.3972296198.

The spelling of 20660421 in words is "twenty million, six hundred sixty thousand, four hundred twenty-one".